Adding upstream version 1.20.14.upstream/1.20.14upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 375 insertions, 0 deletions

diff --git a/src/crypto/rsa/pkcs1v15.go b/src/crypto/rsa/pkcs1v15.go
new file mode 100644
index 0000000..e51b9d2
--- /dev/null
+++ b/src/crypto/rsa/pkcs1v15.go
@@ -0,0 +1,375 @@
+// Copyright 2009 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 rsa
+
+import (
+	"crypto"
+	"crypto/internal/boring"
+	"crypto/internal/randutil"
+	"crypto/subtle"
+	"errors"
+	"io"
+)
+
+// This file implements encryption and decryption using PKCS #1 v1.5 padding.
+
+// PKCS1v15DecryptOptions is for passing options to PKCS #1 v1.5 decryption using
+// the crypto.Decrypter interface.
+type PKCS1v15DecryptOptions struct {
+	// SessionKeyLen is the length of the session key that is being
+	// decrypted. If not zero, then a padding error during decryption will
+	// cause a random plaintext of this length to be returned rather than
+	// an error. These alternatives happen in constant time.
+	SessionKeyLen int
+}
+
+// EncryptPKCS1v15 encrypts the given message with RSA and the padding
+// scheme from PKCS #1 v1.5.  The message must be no longer than the
+// length of the public modulus minus 11 bytes.
+//
+// The random parameter is used as a source of entropy to ensure that
+// encrypting the same message twice doesn't result in the same
+// ciphertext.
+//
+// WARNING: use of this function to encrypt plaintexts other than
+// session keys is dangerous. Use RSA OAEP in new protocols.
+func EncryptPKCS1v15(random io.Reader, pub *PublicKey, msg []byte) ([]byte, error) {
+	randutil.MaybeReadByte(random)
+
+	if err := checkPub(pub); err != nil {
+		return nil, err
+	}
+	k := pub.Size()
+	if len(msg) > k-11 {
+		return nil, ErrMessageTooLong
+	}
+
+	if boring.Enabled && random == boring.RandReader {
+		bkey, err := boringPublicKey(pub)
+		if err != nil {
+			return nil, err
+		}
+		return boring.EncryptRSAPKCS1(bkey, msg)
+	}
+	boring.UnreachableExceptTests()
+
+	// EM = 0x00 || 0x02 || PS || 0x00 || M
+	em := make([]byte, k)
+	em[1] = 2
+	ps, mm := em[2:len(em)-len(msg)-1], em[len(em)-len(msg):]
+	err := nonZeroRandomBytes(ps, random)
+	if err != nil {
+		return nil, err
+	}
+	em[len(em)-len(msg)-1] = 0
+	copy(mm, msg)
+
+	if boring.Enabled {
+		var bkey *boring.PublicKeyRSA
+		bkey, err = boringPublicKey(pub)
+		if err != nil {
+			return nil, err
+		}
+		return boring.EncryptRSANoPadding(bkey, em)
+	}
+
+	return encrypt(pub, em)
+}
+
+// DecryptPKCS1v15 decrypts a plaintext using RSA and the padding scheme from PKCS #1 v1.5.
+// The random parameter is legacy and ignored, and it can be as nil.
+//
+// Note that whether this function returns an error or not discloses secret
+// information. If an attacker can cause this function to run repeatedly and
+// learn whether each instance returned an error then they can decrypt and
+// forge signatures as if they had the private key. See
+// DecryptPKCS1v15SessionKey for a way of solving this problem.
+func DecryptPKCS1v15(random io.Reader, priv *PrivateKey, ciphertext []byte) ([]byte, error) {
+	if err := checkPub(&priv.PublicKey); err != nil {
+		return nil, err
+	}
+
+	if boring.Enabled {
+		bkey, err := boringPrivateKey(priv)
+		if err != nil {
+			return nil, err
+		}
+		out, err := boring.DecryptRSAPKCS1(bkey, ciphertext)
+		if err != nil {
+			return nil, ErrDecryption
+		}
+		return out, nil
+	}
+
+	valid, out, index, err := decryptPKCS1v15(priv, ciphertext)
+	if err != nil {
+		return nil, err
+	}
+	if valid == 0 {
+		return nil, ErrDecryption
+	}
+	return out[index:], nil
+}
+
+// DecryptPKCS1v15SessionKey decrypts a session key using RSA and the padding scheme from PKCS #1 v1.5.
+// The random parameter is legacy and ignored, and it can be as nil.
+// It returns an error if the ciphertext is the wrong length or if the
+// ciphertext is greater than the public modulus. Otherwise, no error is
+// returned. If the padding is valid, the resulting plaintext message is copied
+// into key. Otherwise, key is unchanged. These alternatives occur in constant
+// time. It is intended that the user of this function generate a random
+// session key beforehand and continue the protocol with the resulting value.
+// This will remove any possibility that an attacker can learn any information
+// about the plaintext.
+// See “Chosen Ciphertext Attacks Against Protocols Based on the RSA
+// Encryption Standard PKCS #1”, Daniel Bleichenbacher, Advances in Cryptology
+// (Crypto '98).
+//
+// Note that if the session key is too small then it may be possible for an
+// attacker to brute-force it. If they can do that then they can learn whether
+// a random value was used (because it'll be different for the same ciphertext)
+// and thus whether the padding was correct. This defeats the point of this
+// function. Using at least a 16-byte key will protect against this attack.
+func DecryptPKCS1v15SessionKey(random io.Reader, priv *PrivateKey, ciphertext []byte, key []byte) error {
+	if err := checkPub(&priv.PublicKey); err != nil {
+		return err
+	}
+	k := priv.Size()
+	if k-(len(key)+3+8) < 0 {
+		return ErrDecryption
+	}
+
+	valid, em, index, err := decryptPKCS1v15(priv, ciphertext)
+	if err != nil {
+		return err
+	}
+
+	if len(em) != k {
+		// This should be impossible because decryptPKCS1v15 always
+		// returns the full slice.
+		return ErrDecryption
+	}
+
+	valid &= subtle.ConstantTimeEq(int32(len(em)-index), int32(len(key)))
+	subtle.ConstantTimeCopy(valid, key, em[len(em)-len(key):])
+	return nil
+}
+
+// decryptPKCS1v15 decrypts ciphertext using priv. It returns one or zero in
+// valid that indicates whether the plaintext was correctly structured.
+// In either case, the plaintext is returned in em so that it may be read
+// independently of whether it was valid in order to maintain constant memory
+// access patterns. If the plaintext was valid then index contains the index of
+// the original message in em, to allow constant time padding removal.
+func decryptPKCS1v15(priv *PrivateKey, ciphertext []byte) (valid int, em []byte, index int, err error) {
+	k := priv.Size()
+	if k < 11 {
+		err = ErrDecryption
+		return
+	}
+
+	if boring.Enabled {
+		var bkey *boring.PrivateKeyRSA
+		bkey, err = boringPrivateKey(priv)
+		if err != nil {
+			return
+		}
+		em, err = boring.DecryptRSANoPadding(bkey, ciphertext)
+		if err != nil {
+			return
+		}
+	} else {
+		em, err = decrypt(priv, ciphertext, noCheck)
+		if err != nil {
+			return
+		}
+	}
+
+	firstByteIsZero := subtle.ConstantTimeByteEq(em[0], 0)
+	secondByteIsTwo := subtle.ConstantTimeByteEq(em[1], 2)
+
+	// The remainder of the plaintext must be a string of non-zero random
+	// octets, followed by a 0, followed by the message.
+	//   lookingForIndex: 1 iff we are still looking for the zero.
+	//   index: the offset of the first zero byte.
+	lookingForIndex := 1
+
+	for i := 2; i < len(em); i++ {
+		equals0 := subtle.ConstantTimeByteEq(em[i], 0)
+		index = subtle.ConstantTimeSelect(lookingForIndex&equals0, i, index)
+		lookingForIndex = subtle.ConstantTimeSelect(equals0, 0, lookingForIndex)
+	}
+
+	// The PS padding must be at least 8 bytes long, and it starts two
+	// bytes into em.
+	validPS := subtle.ConstantTimeLessOrEq(2+8, index)
+
+	valid = firstByteIsZero & secondByteIsTwo & (^lookingForIndex & 1) & validPS
+	index = subtle.ConstantTimeSelect(valid, index+1, 0)
+	return valid, em, index, nil
+}
+
+// nonZeroRandomBytes fills the given slice with non-zero random octets.
+func nonZeroRandomBytes(s []byte, random io.Reader) (err error) {
+	_, err = io.ReadFull(random, s)
+	if err != nil {
+		return
+	}
+
+	for i := 0; i < len(s); i++ {
+		for s[i] == 0 {
+			_, err = io.ReadFull(random, s[i:i+1])
+			if err != nil {
+				return
+			}
+			// In tests, the PRNG may return all zeros so we do
+			// this to break the loop.
+			s[i] ^= 0x42
+		}
+	}
+
+	return
+}
+
+// These are ASN1 DER structures:
+//
+//	DigestInfo ::= SEQUENCE {
+//	  digestAlgorithm AlgorithmIdentifier,
+//	  digest OCTET STRING
+//	}
+//
+// For performance, we don't use the generic ASN1 encoder. Rather, we
+// precompute a prefix of the digest value that makes a valid ASN1 DER string
+// with the correct contents.
+var hashPrefixes = map[crypto.Hash][]byte{
+	crypto.MD5:       {0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, 0x05, 0x00, 0x04, 0x10},
+	crypto.SHA1:      {0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05, 0x00, 0x04, 0x14},
+	crypto.SHA224:    {0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04, 0x05, 0x00, 0x04, 0x1c},
+	crypto.SHA256:    {0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20},
+	crypto.SHA384:    {0x30, 0x41, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02, 0x05, 0x00, 0x04, 0x30},
+	crypto.SHA512:    {0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, 0x05, 0x00, 0x04, 0x40},
+	crypto.MD5SHA1:   {}, // A special TLS case which doesn't use an ASN1 prefix.
+	crypto.RIPEMD160: {0x30, 0x20, 0x30, 0x08, 0x06, 0x06, 0x28, 0xcf, 0x06, 0x03, 0x00, 0x31, 0x04, 0x14},
+}
+
+// SignPKCS1v15 calculates the signature of hashed using
+// RSASSA-PKCS1-V1_5-SIGN from RSA PKCS #1 v1.5.  Note that hashed must
+// be the result of hashing the input message using the given hash
+// function. If hash is zero, hashed is signed directly. This isn't
+// advisable except for interoperability.
+//
+// The random parameter is legacy and ignored, and it can be as nil.
+//
+// This function is deterministic. Thus, if the set of possible
+// messages is small, an attacker may be able to build a map from
+// messages to signatures and identify the signed messages. As ever,
+// signatures provide authenticity, not confidentiality.
+func SignPKCS1v15(random io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte) ([]byte, error) {
+	hashLen, prefix, err := pkcs1v15HashInfo(hash, len(hashed))
+	if err != nil {
+		return nil, err
+	}
+
+	tLen := len(prefix) + hashLen
+	k := priv.Size()
+	if k < tLen+11 {
+		return nil, ErrMessageTooLong
+	}
+
+	if boring.Enabled {
+		bkey, err := boringPrivateKey(priv)
+		if err != nil {
+			return nil, err
+		}
+		return boring.SignRSAPKCS1v15(bkey, hash, hashed)
+	}
+
+	// EM = 0x00 || 0x01 || PS || 0x00 || T
+	em := make([]byte, k)
+	em[1] = 1
+	for i := 2; i < k-tLen-1; i++ {
+		em[i] = 0xff
+	}
+	copy(em[k-tLen:k-hashLen], prefix)
+	copy(em[k-hashLen:k], hashed)
+
+	return decrypt(priv, em, withCheck)
+}
+
+// VerifyPKCS1v15 verifies an RSA PKCS #1 v1.5 signature.
+// hashed is the result of hashing the input message using the given hash
+// function and sig is the signature. A valid signature is indicated by
+// returning a nil error. If hash is zero then hashed is used directly. This
+// isn't advisable except for interoperability.
+func VerifyPKCS1v15(pub *PublicKey, hash crypto.Hash, hashed []byte, sig []byte) error {
+	if boring.Enabled {
+		bkey, err := boringPublicKey(pub)
+		if err != nil {
+			return err
+		}
+		if err := boring.VerifyRSAPKCS1v15(bkey, hash, hashed, sig); err != nil {
+			return ErrVerification
+		}
+		return nil
+	}
+
+	hashLen, prefix, err := pkcs1v15HashInfo(hash, len(hashed))
+	if err != nil {
+		return err
+	}
+
+	tLen := len(prefix) + hashLen
+	k := pub.Size()
+	if k < tLen+11 {
+		return ErrVerification
+	}
+
+	// RFC 8017 Section 8.2.2: If the length of the signature S is not k
+	// octets (where k is the length in octets of the RSA modulus n), output
+	// "invalid signature" and stop.
+	if k != len(sig) {
+		return ErrVerification
+	}
+
+	em, err := encrypt(pub, sig)
+	if err != nil {
+		return ErrVerification
+	}
+	// EM = 0x00 || 0x01 || PS || 0x00 || T
+
+	ok := subtle.ConstantTimeByteEq(em[0], 0)
+	ok &= subtle.ConstantTimeByteEq(em[1], 1)
+	ok &= subtle.ConstantTimeCompare(em[k-hashLen:k], hashed)
+	ok &= subtle.ConstantTimeCompare(em[k-tLen:k-hashLen], prefix)
+	ok &= subtle.ConstantTimeByteEq(em[k-tLen-1], 0)
+
+	for i := 2; i < k-tLen-1; i++ {
+		ok &= subtle.ConstantTimeByteEq(em[i], 0xff)
+	}
+
+	if ok != 1 {
+		return ErrVerification
+	}
+
+	return nil
+}
+
+func pkcs1v15HashInfo(hash crypto.Hash, inLen int) (hashLen int, prefix []byte, err error) {
+	// Special case: crypto.Hash(0) is used to indicate that the data is
+	// signed directly.
+	if hash == 0 {
+		return inLen, nil, nil
+	}
+
+	hashLen = hash.Size()
+	if inLen != hashLen {
+		return 0, nil, errors.New("crypto/rsa: input must be hashed message")
+	}
+	prefix, ok := hashPrefixes[hash]
+	if !ok {
+		return 0, nil, errors.New("crypto/rsa: unsupported hash function")
+	}
+	return
+}