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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tls
import (
"crypto/ecdsa"
"crypto/internal/boring/fipstls"
"crypto/rsa"
"crypto/x509"
)
// needFIPS returns fipstls.Required(); it avoids a new import in common.go.
func needFIPS() bool {
return fipstls.Required()
}
// fipsMinVersion replaces c.minVersion in FIPS-only mode.
func fipsMinVersion(c *Config) uint16 {
// FIPS requires TLS 1.2.
return VersionTLS12
}
// fipsMaxVersion replaces c.maxVersion in FIPS-only mode.
func fipsMaxVersion(c *Config) uint16 {
// FIPS requires TLS 1.2.
return VersionTLS12
}
// default defaultFIPSCurvePreferences is the FIPS-allowed curves,
// in preference order (most preferable first).
var defaultFIPSCurvePreferences = []CurveID{CurveP256, CurveP384, CurveP521}
// fipsCurvePreferences replaces c.curvePreferences in FIPS-only mode.
func fipsCurvePreferences(c *Config) []CurveID {
if c == nil || len(c.CurvePreferences) == 0 {
return defaultFIPSCurvePreferences
}
var list []CurveID
for _, id := range c.CurvePreferences {
for _, allowed := range defaultFIPSCurvePreferences {
if id == allowed {
list = append(list, id)
break
}
}
}
return list
}
// default FIPSCipherSuites is the FIPS-allowed cipher suites,
// in preference order (most preferable first).
var defaultFIPSCipherSuites = []uint16{
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
TLS_RSA_WITH_AES_128_GCM_SHA256,
TLS_RSA_WITH_AES_256_GCM_SHA384,
}
// fipsCipherSuites replaces c.cipherSuites in FIPS-only mode.
func fipsCipherSuites(c *Config) []uint16 {
if c == nil || c.CipherSuites == nil {
return defaultFIPSCipherSuites
}
var list []uint16
for _, id := range c.CipherSuites {
for _, allowed := range defaultFIPSCipherSuites {
if id == allowed {
list = append(list, id)
break
}
}
}
return list
}
// isBoringCertificate reports whether a certificate may be used
// when constructing a verified chain.
// It is called for each leaf, intermediate, and root certificate.
func isBoringCertificate(c *x509.Certificate) bool {
if !needFIPS() {
// Everything is OK if we haven't forced FIPS-only mode.
return true
}
// Otherwise the key must be RSA 2048, RSA 3072, or ECDSA P-256.
switch k := c.PublicKey.(type) {
default:
return false
case *rsa.PublicKey:
if size := k.N.BitLen(); size != 2048 && size != 3072 {
return false
}
case *ecdsa.PublicKey:
if name := k.Curve.Params().Name; name != "P-256" && name != "P-384" {
return false
}
}
return true
}
// supportedSignatureAlgorithms returns the supported signature algorithms.
// It knows that the FIPS-allowed ones are all at the beginning of
// defaultSupportedSignatureAlgorithms.
func supportedSignatureAlgorithms() []signatureAndHash {
all := defaultSupportedSignatureAlgorithms
if !needFIPS() {
return all
}
i := 0
for i < len(all) && all[i].hash != hashSHA1 {
i++
}
return all[:i]
}
var testingOnlyForceClientHelloSignatureAndHashes []signatureAndHash