119 lines
3.9 KiB
Go
119 lines
3.9 KiB
Go
// Copyright 2014 ISRG. All rights reserved
|
|
// This Source Code Form is subject to the terms of the Mozilla Public
|
|
// License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
|
|
|
|
package core
|
|
|
|
import (
|
|
"crypto"
|
|
"crypto/ecdsa"
|
|
"crypto/rsa"
|
|
"fmt"
|
|
blog "github.com/letsencrypt/boulder/log"
|
|
"math/big"
|
|
"reflect"
|
|
"sync"
|
|
)
|
|
|
|
// To generate, run: primes 2 752 | tr '\n' ,
|
|
var smallPrimeInts = []int64{
|
|
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47,
|
|
53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107,
|
|
109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167,
|
|
173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229,
|
|
233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283,
|
|
293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359,
|
|
367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431,
|
|
433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491,
|
|
499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571,
|
|
577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641,
|
|
643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709,
|
|
719, 727, 733, 739, 743, 751,
|
|
}
|
|
|
|
// singleton defines the object of a Singleton pattern
|
|
var (
|
|
smallPrimesSingleton sync.Once
|
|
smallPrimes []*big.Int
|
|
)
|
|
|
|
// GoodKey returns true iff the key is acceptable for both TLS use and account
|
|
// key use (our requirements are the same for either one), according to basic
|
|
// strength and algorithm checking.
|
|
// TODO: Support JsonWebKeys once go-jose migration is done.
|
|
func GoodKey(key crypto.PublicKey) error {
|
|
log := blog.GetAuditLogger()
|
|
switch t := key.(type) {
|
|
case rsa.PublicKey:
|
|
return GoodKeyRSA(t)
|
|
case *rsa.PublicKey:
|
|
return GoodKeyRSA(*t)
|
|
case ecdsa.PublicKey:
|
|
return GoodKeyECDSA(t)
|
|
case *ecdsa.PublicKey:
|
|
return GoodKeyECDSA(*t)
|
|
default:
|
|
err := MalformedRequestError(fmt.Sprintf("Unknown key type %s", reflect.TypeOf(key)))
|
|
log.Debug(err.Error())
|
|
return err
|
|
}
|
|
}
|
|
|
|
// GoodKeyECDSA determines if an ECDSA pubkey meets our requirements
|
|
func GoodKeyECDSA(key ecdsa.PublicKey) (err error) {
|
|
log := blog.GetAuditLogger()
|
|
err = NotSupportedError("ECDSA keys not yet supported")
|
|
log.Debug(err.Error())
|
|
return
|
|
}
|
|
|
|
// GoodKeyRSA determines if a RSA pubkey meets our requirements
|
|
func GoodKeyRSA(key rsa.PublicKey) (err error) {
|
|
log := blog.GetAuditLogger()
|
|
// Baseline Requirements Appendix A
|
|
// Modulus must be >= 2048 bits and <= 4096 bits
|
|
modulus := key.N
|
|
modulusBitLen := modulus.BitLen()
|
|
const maxKeySize = 4096
|
|
if modulusBitLen < 2048 {
|
|
err = MalformedRequestError(fmt.Sprintf("Key too small: %d", modulusBitLen))
|
|
log.Debug(err.Error())
|
|
return err
|
|
}
|
|
if modulusBitLen > maxKeySize {
|
|
err = MalformedRequestError(fmt.Sprintf("Key too large: %d > %d", modulusBitLen, maxKeySize))
|
|
log.Debug(err.Error())
|
|
return err
|
|
}
|
|
// The CA SHALL confirm that the value of the public exponent is an
|
|
// odd number equal to 3 or more. Additionally, the public exponent
|
|
// SHOULD be in the range between 2^16 + 1 and 2^256-1.
|
|
// NOTE: rsa.PublicKey cannot represent an exponent part greater than
|
|
// 2^32 - 1 or 2^64 - 1, because it stores E as an integer. So we
|
|
// don't need to check the upper bound.
|
|
if (key.E%2) == 0 || key.E < ((1<<16)+1) {
|
|
err = MalformedRequestError(fmt.Sprintf("Key exponent should be odd and >2^16: %d", key.E))
|
|
log.Debug(err.Error())
|
|
return err
|
|
}
|
|
// The modulus SHOULD also have the following characteristics: an odd
|
|
// number, not the power of a prime, and have no factors smaller than 752.
|
|
// TODO: We don't yet check for "power of a prime."
|
|
smallPrimesSingleton.Do(func() {
|
|
for _, prime := range smallPrimeInts {
|
|
smallPrimes = append(smallPrimes, big.NewInt(prime))
|
|
}
|
|
})
|
|
for _, prime := range smallPrimes {
|
|
var result big.Int
|
|
result.Mod(modulus, prime)
|
|
if result.Sign() == 0 {
|
|
err = MalformedRequestError(fmt.Sprintf("Key divisible by small prime: %d", prime))
|
|
log.Debug(err.Error())
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|