mirror of
https://github.com/square/certigo.git
synced 2024-04-21 12:32:40 +00:00
457 lines
15 KiB
Go
457 lines
15 KiB
Go
/*-
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* Copyright 2016 Square Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package lib
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import (
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"bytes"
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"crypto/dsa"
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"crypto/ecdsa"
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"crypto/rsa"
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"crypto/tls"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/hex"
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"encoding/json"
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"encoding/pem"
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"fmt"
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"net"
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"strconv"
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"strings"
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"time"
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)
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var keyUsages = []x509.KeyUsage{
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x509.KeyUsageDigitalSignature,
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x509.KeyUsageContentCommitment,
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x509.KeyUsageKeyEncipherment,
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x509.KeyUsageDataEncipherment,
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x509.KeyUsageKeyAgreement,
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x509.KeyUsageCertSign,
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x509.KeyUsageCRLSign,
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x509.KeyUsageEncipherOnly,
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x509.KeyUsageDecipherOnly,
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}
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var signatureSchemeStrings = map[tls.SignatureScheme]string{
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// As per RFC 5246 (TLS v1.2), the handshake contains a set of
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// SignatureAndHashAlgorithm values which is a tuple of a hash
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// and a signature algorithm each. Go takes these values and
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// maps them into a tls.SignatureScheme value, where the upper
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// 8 bits are hash and lower 8 bits are the signature.
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//
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// TLS v1.3 changes this to use the signature_algorithms extension,
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// see draft-ietf-tls-tls13-18 section 4.2.3. These are 16-bit
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// values that explicitly specify a signature algorithm.
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//
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// cf. RFC 5246, Section A.4.1
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// cf. draft-ietf-tls-tls13-18, Section 4.2.3
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// cf. RFC 5758, Section 2
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//
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// See also ssl/ssl_locl.h in OpenSSL (grep for TLSEXT_SIGALG).
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//
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// Common values:
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// --
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// Signatures:
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// 0x0 anonymous
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// 0x1 RSA
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// 0x2 DSA
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// 0x3 ECDSA
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// --
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// Hashes:
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// 0x0 none
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// 0x1 MD-5
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// 0x2 SHA-1
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// 0x3 SHA-224
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// 0x4 SHA-256
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// 0x5 SHA-384
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// 0x6 SHA-512
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// --
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// TLS v1.3:
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// 0x0807 ED25519
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// 0x0808 ED448
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// 0xFE00-0xFFFF Private use
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// --
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tls.PKCS1WithSHA1: "RSA-PKCS1 with SHA1",
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tls.PKCS1WithSHA256: "RSA-PKCS1 with SHA256",
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tls.PKCS1WithSHA384: "RSA-PKCS1 with SHA384",
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tls.PKCS1WithSHA512: "RSA-PKCS1 with SHA512",
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tls.PSSWithSHA256: "RSA-PSS with SHA256",
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tls.PSSWithSHA384: "RSA-PSS with SHA384",
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tls.PSSWithSHA512: "RSA-PSS with SHA512",
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tls.ECDSAWithP256AndSHA256: "ECDSA with P256 and SHA256",
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tls.ECDSAWithP384AndSHA384: "ECDSA with P384 and SHA384",
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tls.ECDSAWithP521AndSHA512: "ECDSA with P521 and SHA512",
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// Not from stdlib
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// Defined in TLS 1.3 draft
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0x807: "ED25519",
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0x808: "ED448",
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// Not in stdlib: server sent {sha1,ecdsa} or {sha224,ecdsa}.
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0x203: "ECDSA with SHA1",
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0x303: "ECDSA with SHA224",
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// Unused (?) but theorically possible combos (per RFC 5246)
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0x101: "RSA-PKCS1 with MD5",
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0x301: "RSA-PKCS1 with SHA224",
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0x102: "DSA with MD5",
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0x202: "DSA with SHA1",
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0x302: "DSA with SHA224",
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0x402: "DSA with SHA256",
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0x502: "DSA with SHA384",
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0x602: "DSA with SHA512",
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// Funky stuff supported by OpenSSL
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0xeeee: "GOST 34.10-2012 (256)",
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0xefef: "GOST 34.10-2012 (512)",
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0xeded: "GOST 34.10-2001",
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}
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var keyUsageStrings = map[x509.KeyUsage]string{
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x509.KeyUsageDigitalSignature: "Digital Signature",
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x509.KeyUsageContentCommitment: "Content Commitment",
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x509.KeyUsageKeyEncipherment: "Key Encipherment",
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x509.KeyUsageDataEncipherment: "Data Encipherment",
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x509.KeyUsageKeyAgreement: "Key Agreement",
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x509.KeyUsageCertSign: "Cert Sign",
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x509.KeyUsageCRLSign: "CRL Sign",
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x509.KeyUsageEncipherOnly: "Encipher Only",
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x509.KeyUsageDecipherOnly: "Decipher Only",
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}
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var extKeyUsageStrings = map[x509.ExtKeyUsage]string{
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x509.ExtKeyUsageAny: "Any",
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x509.ExtKeyUsageServerAuth: "Server Auth",
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x509.ExtKeyUsageClientAuth: "Client Auth",
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x509.ExtKeyUsageCodeSigning: "Code Signing",
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x509.ExtKeyUsageEmailProtection: "Email Protection",
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x509.ExtKeyUsageIPSECEndSystem: "IPSEC End System",
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x509.ExtKeyUsageIPSECTunnel: "IPSEC Tunnel",
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x509.ExtKeyUsageIPSECUser: "IPSEC User",
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x509.ExtKeyUsageTimeStamping: "Time Stamping",
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x509.ExtKeyUsageOCSPSigning: "OCSP Signing",
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x509.ExtKeyUsageMicrosoftServerGatedCrypto: "Microsoft ServerGatedCrypto",
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x509.ExtKeyUsageNetscapeServerGatedCrypto: "Netscape ServerGatedCrypto",
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}
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var algoName = [...]string{
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x509.MD2WithRSA: "MD2-RSA",
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x509.MD5WithRSA: "MD5-RSA",
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x509.SHA1WithRSA: "SHA1-RSA",
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x509.SHA256WithRSA: "SHA256-RSA",
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x509.SHA384WithRSA: "SHA384-RSA",
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x509.SHA512WithRSA: "SHA512-RSA",
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x509.DSAWithSHA1: "DSA-SHA1",
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x509.DSAWithSHA256: "DSA-SHA256",
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x509.ECDSAWithSHA1: "ECDSA-SHA1",
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x509.ECDSAWithSHA256: "ECDSA-SHA256",
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x509.ECDSAWithSHA384: "ECDSA-SHA384",
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x509.ECDSAWithSHA512: "ECDSA-SHA512",
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x509.PureEd25519: "ED25519",
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}
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type basicConstraints struct {
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IsCA bool `json:"is_ca"`
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MaxPathLen *int `json:"pathlen,omitempty"`
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}
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type nameConstraints struct {
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Critical bool `json:"critical,omitempty"`
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PermittedDNSDomains []string `json:"permitted_dns_domains,omitempty"`
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ExcludedDNSDomains []string `json:"excluded_dns_domains,omitempty"`
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PermittedIPRanges []*net.IPNet `json:"permitted_ip_ranges,omitempty"`
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ExcludedIPRanges []*net.IPNet `json:"excluded_ip_ranges,omitempty"`
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PermittedEmailAddresses []string `json:"permitted_email_addresses,omitempty"`
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ExcludedEmailAddresses []string `json:"excluded_email_addresses,omitempty"`
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PermittedURIDomains []string `json:"permitted_uri_domains,omitempty"`
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ExcludedURIDomains []string `json:"excluded_uri_domains,omitempty"`
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}
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// simpleCertificate is a JSON-representable certificate metadata holder.
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type simpleCertificate struct {
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Alias string `json:"alias,omitempty"`
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SerialNumber string `json:"serial"`
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NotBefore time.Time `json:"not_before"`
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NotAfter time.Time `json:"not_after"`
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SignatureAlgorithm simpleSigAlg `json:"signature_algorithm"`
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IsSelfSigned bool `json:"is_self_signed"`
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Subject simplePKIXName `json:"subject"`
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Issuer simplePKIXName `json:"issuer"`
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BasicConstraints *basicConstraints `json:"basic_constraints,omitempty"`
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NameConstraints *nameConstraints `json:"name_constraints,omitempty"`
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OCSPServer []string `json:"ocsp_server,omitempty"`
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IssuingCertificateURL []string `json:"issuing_certificate,omitempty"`
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KeyUsage simpleKeyUsage `json:"key_usage,omitempty"`
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ExtKeyUsage []simpleExtKeyUsage `json:"extended_key_usage,omitempty"`
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AltDNSNames []string `json:"dns_names,omitempty"`
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AltIPAddresses []net.IP `json:"ip_addresses,omitempty"`
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URINames []string `json:"uri_names,omitempty"`
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EmailAddresses []string `json:"email_addresses,omitempty"`
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SCTList []*simpleSCT `json:"sct_list,omitempty"`
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Warnings []string `json:"warnings,omitempty"`
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PEM string `json:"pem,omitempty"`
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// Internal fields for text display. Set - to skip serialize.
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Width int `json:"-"`
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}
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type simpleSCT struct {
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Version uint64 `json:"version"`
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LogOperator string `json:"log_operator,omitempty"`
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LogURL string `json:"log_url,omitempty"`
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LogID []byte `json:"log_id"`
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Timestamp time.Time `json:"timestamp"`
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SignatureAlgorithm simpleSigAlg `json:"signature_algorithm"`
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}
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type simplePKIXName struct {
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Name pkix.Name
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KeyID []byte
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}
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type simpleKeyUsage x509.KeyUsage
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type simpleExtKeyUsage x509.ExtKeyUsage
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type simpleSigAlg x509.SignatureAlgorithm
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func createSimpleCertificate(name string, cert *x509.Certificate) simpleCertificate {
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out := simpleCertificate{
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Alias: name,
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SerialNumber: cert.SerialNumber.String(),
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NotBefore: cert.NotBefore,
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NotAfter: cert.NotAfter,
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SignatureAlgorithm: simpleSigAlg(cert.SignatureAlgorithm),
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IsSelfSigned: IsSelfSigned(cert),
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Subject: simplePKIXName{
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Name: cert.Subject,
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KeyID: cert.SubjectKeyId,
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},
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Issuer: simplePKIXName{
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Name: cert.Issuer,
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KeyID: cert.AuthorityKeyId,
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},
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KeyUsage: simpleKeyUsage(cert.KeyUsage),
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OCSPServer: cert.OCSPServer,
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IssuingCertificateURL: cert.IssuingCertificateURL,
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AltDNSNames: cert.DNSNames,
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AltIPAddresses: cert.IPAddresses,
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EmailAddresses: cert.EmailAddresses,
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SCTList: parseSCTList(cert),
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PEM: string(pem.EncodeToMemory(EncodeX509ToPEM(cert, nil))),
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}
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for _, uri := range cert.URIs {
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out.URINames = append(out.URINames, uri.String())
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}
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out.Warnings = certWarnings(cert, out.URINames)
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if cert.BasicConstraintsValid {
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out.BasicConstraints = &basicConstraints{
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IsCA: cert.IsCA,
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}
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if cert.MaxPathLen > 0 || cert.MaxPathLenZero {
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out.BasicConstraints.MaxPathLen = &cert.MaxPathLen
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}
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}
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if len(cert.PermittedDNSDomains) > 0 || len(cert.ExcludedDNSDomains) > 0 ||
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len(cert.PermittedIPRanges) > 0 || len(cert.ExcludedIPRanges) > 0 ||
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len(cert.PermittedEmailAddresses) > 0 || len(cert.ExcludedEmailAddresses) > 0 ||
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len(cert.PermittedURIDomains) > 0 || len(cert.ExcludedURIDomains) > 0 {
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out.NameConstraints = &nameConstraints{
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Critical: cert.PermittedDNSDomainsCritical,
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PermittedDNSDomains: cert.PermittedDNSDomains,
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ExcludedDNSDomains: cert.ExcludedDNSDomains,
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PermittedIPRanges: cert.PermittedIPRanges,
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ExcludedIPRanges: cert.ExcludedIPRanges,
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PermittedEmailAddresses: cert.PermittedEmailAddresses,
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ExcludedEmailAddresses: cert.ExcludedEmailAddresses,
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PermittedURIDomains: cert.PermittedURIDomains,
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ExcludedURIDomains: cert.ExcludedURIDomains,
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}
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}
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simpleEku := []simpleExtKeyUsage{}
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for _, eku := range cert.ExtKeyUsage {
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simpleEku = append(simpleEku, simpleExtKeyUsage(eku))
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}
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out.ExtKeyUsage = simpleEku
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return out
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}
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func (p simplePKIXName) MarshalJSON() ([]byte, error) {
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out := map[string]interface{}{}
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for _, rdn := range p.Name.Names {
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oid := describeOid(rdn.Type)
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if prev, ok := out[oid.Slug]; oid.Multiple && ok {
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l := prev.([]interface{})
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out[oid.Slug] = append(l, rdn.Value)
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} else if oid.Multiple {
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out[oid.Slug] = []interface{}{rdn.Value}
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} else {
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out[oid.Slug] = rdn.Value
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}
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}
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if len(p.KeyID) > 0 {
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out["key_id"] = hexify(p.KeyID)
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}
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return json.Marshal(out)
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}
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func (k simpleKeyUsage) MarshalJSON() ([]byte, error) {
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return json.Marshal(keyUsage(k))
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}
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func (e simpleExtKeyUsage) MarshalJSON() ([]byte, error) {
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return json.Marshal(extKeyUsage(e))
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}
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func (s simpleSigAlg) MarshalJSON() ([]byte, error) {
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return json.Marshal(algString(x509.SignatureAlgorithm(s)))
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}
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// hexify returns a colon separated, hexadecimal representation
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// of a given byte array.
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func hexify(arr []byte) string {
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var hexed bytes.Buffer
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for i := 0; i < len(arr); i++ {
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hexed.WriteString(strings.ToUpper(hex.EncodeToString(arr[i : i+1])))
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if i < len(arr)-1 {
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hexed.WriteString(":")
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}
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}
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return hexed.String()
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}
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// keyUsage decodes/prints key usage from a certificate.
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func keyUsage(sKu simpleKeyUsage) []string {
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ku := x509.KeyUsage(sKu)
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out := []string{}
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for _, key := range keyUsages {
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if ku&key > 0 {
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out = append(out, keyUsageStrings[key])
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}
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}
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return out
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}
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// extKeyUsage decodes/prints extended key usage from a certificate.
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func extKeyUsage(sEku simpleExtKeyUsage) string {
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eku := x509.ExtKeyUsage(sEku)
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val, ok := extKeyUsageStrings[eku]
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if ok {
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return val
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}
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return fmt.Sprintf("unknown:%d", eku)
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}
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func algString(algo x509.SignatureAlgorithm) string {
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if 0 < algo && int(algo) < len(algoName) {
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return algoName[algo]
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}
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return strconv.Itoa(int(algo))
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}
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// decodeKey returns the algorithm and key size for a public key.
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func decodeKey(publicKey interface{}) (string, int) {
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switch pk := publicKey.(type) {
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case *dsa.PublicKey:
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return "DSA", pk.P.BitLen()
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case *ecdsa.PublicKey:
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return "ECDSA", pk.Curve.Params().BitSize
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case *rsa.PublicKey:
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return "RSA", pk.N.BitLen()
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default:
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return "", 0
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}
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}
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// certWarnings prints a list of warnings to show common mistakes in certs.
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func certWarnings(cert *x509.Certificate, uriNames []string) (warnings []string) {
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if cert.SerialNumber.Sign() != 1 {
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warnings = append(warnings, "Serial number in cert appears to be zero/negative")
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}
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if cert.SerialNumber.BitLen() > 160 {
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warnings = append(warnings, "Serial number too long; should be 20 bytes or less")
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}
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if cert.KeyUsage&x509.KeyUsageCertSign != 0 && !cert.IsCA {
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warnings = append(warnings, "Key usage 'cert sign' is set, but is not a CA cert")
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}
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if cert.KeyUsage&x509.KeyUsageCertSign == 0 && cert.IsCA {
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warnings = append(warnings, "Certificate is a CA cert, but key usage 'cert sign' missing")
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}
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if cert.Version < 2 {
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warnings = append(warnings, fmt.Sprintf("Certificate is not in X509v3 format (version is %d)", cert.Version+1))
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}
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if len(cert.DNSNames) == 0 && len(cert.IPAddresses) == 0 && len(uriNames) == 0 && !cert.IsCA {
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warnings = append(warnings, "Certificate doesn't have any valid DNS/URI names or IP addresses set")
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}
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if len(cert.UnhandledCriticalExtensions) > 0 {
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warnings = append(warnings, "Certificate has unhandled critical extensions")
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}
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warnings = append(warnings, algWarnings(cert)...)
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return
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}
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// algWarnings checks key sizes, signature algorithms.
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func algWarnings(cert *x509.Certificate) (warnings []string) {
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alg, size := decodeKey(cert.PublicKey)
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if (alg == "RSA" || alg == "DSA") && size < 2048 {
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warnings = append(warnings, fmt.Sprintf("Size of %s key should be at least 2048 bits", alg))
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}
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if alg == "ECDSA" && size < 224 {
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warnings = append(warnings, fmt.Sprintf("Size of %s key should be at least 224 bits", alg))
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}
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for _, alg := range badSignatureAlgorithms {
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if cert.SignatureAlgorithm == alg {
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warnings = append(warnings, fmt.Sprintf("Signed with %s, which is an outdated signature algorithm", algString(alg)))
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}
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}
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if alg == "RSA" {
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key := cert.PublicKey.(*rsa.PublicKey)
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if key.E < 3 {
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warnings = append(warnings, "Public key exponent in RSA key is less than 3")
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}
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if key.N.Sign() != 1 {
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warnings = append(warnings, "Public key modulus in RSA key appears to be zero/negative")
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}
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}
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return
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}
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// IsSelfSigned returns true iff the given certificate has a valid self-signature.
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func IsSelfSigned(cert *x509.Certificate) bool {
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return cert.CheckSignatureFrom(cert) == nil
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}
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