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authorCory Fields <cory-nospam-@coryfields.com>2015-03-20 00:49:13 -0400
committerPieter Wuille <pieter.wuille@gmail.com>2016-05-13 10:23:03 +0200
commit27a212dcb4fe842ead77d01b98f2c1a58ecca609 (patch)
tree4f1afa080592b352e84fc52d5871034cac5b5cf8 /src/crypto
parent6bec172eb95e195847bb6dd6d4e62ada79c98c6d (diff)
crypto: add AES 128/256 CBC classes
The output should always match openssl's, even for failed operations. Even for a decrypt with broken padding, the output is always deterministic (and attemtps to be constant-time).
Diffstat (limited to 'src/crypto')
-rw-r--r--src/crypto/aes.cpp144
-rw-r--r--src/crypto/aes.h52
2 files changed, 196 insertions, 0 deletions
diff --git a/src/crypto/aes.cpp b/src/crypto/aes.cpp
index 035abd75bd..1d469d0fb4 100644
--- a/src/crypto/aes.cpp
+++ b/src/crypto/aes.cpp
@@ -71,3 +71,147 @@ void AES256Decrypt::Decrypt(unsigned char plaintext[16], const unsigned char cip
{
AES256_decrypt(&ctx, 1, plaintext, ciphertext);
}
+
+
+template <typename T>
+static int CBCEncrypt(const T& enc, const unsigned char iv[AES_BLOCKSIZE], const unsigned char* data, int size, bool pad, unsigned char* out)
+{
+ int written = 0;
+ int padsize = size % AES_BLOCKSIZE;
+ unsigned char mixed[AES_BLOCKSIZE];
+
+ if (!data || !size || !out)
+ return 0;
+
+ if (!pad && padsize != 0)
+ return 0;
+
+ memcpy(mixed, iv, AES_BLOCKSIZE);
+
+ // Write all but the last block
+ while (written + AES_BLOCKSIZE <= size) {
+ for (int i = 0; i != AES_BLOCKSIZE; i++)
+ mixed[i] ^= *data++;
+ enc.Encrypt(out + written, mixed);
+ memcpy(mixed, out + written, AES_BLOCKSIZE);
+ written += AES_BLOCKSIZE;
+ }
+ if (pad) {
+ // For all that remains, pad each byte with the value of the remaining
+ // space. If there is none, pad by a full block.
+ for (int i = 0; i != padsize; i++)
+ mixed[i] ^= *data++;
+ for (int i = padsize; i != AES_BLOCKSIZE; i++)
+ mixed[i] ^= AES_BLOCKSIZE - padsize;
+ enc.Encrypt(out + written, mixed);
+ written += AES_BLOCKSIZE;
+ }
+ return written;
+}
+
+template <typename T>
+static int CBCDecrypt(const T& dec, const unsigned char iv[AES_BLOCKSIZE], const unsigned char* data, int size, bool pad, unsigned char* out)
+{
+ unsigned char padsize = 0;
+ int written = 0;
+ bool fail = false;
+ const unsigned char* prev = iv;
+
+ if (!data || !size || !out)
+ return 0;
+
+ if (size % AES_BLOCKSIZE != 0)
+ return 0;
+
+ // Decrypt all data. Padding will be checked in the output.
+ while (written != size) {
+ dec.Decrypt(out, data + written);
+ for (int i = 0; i != AES_BLOCKSIZE; i++)
+ *out++ ^= prev[i];
+ prev = data + written;
+ written += AES_BLOCKSIZE;
+ }
+
+ // When decrypting padding, attempt to run in constant-time
+ if (pad) {
+ // If used, padding size is the value of the last decrypted byte. For
+ // it to be valid, It must be between 1 and AES_BLOCKSIZE.
+ padsize = *--out;
+ fail = !padsize | (padsize > AES_BLOCKSIZE);
+
+ // If not well-formed, treat it as though there's no padding.
+ padsize *= !fail;
+
+ // All padding must equal the last byte otherwise it's not well-formed
+ for (int i = AES_BLOCKSIZE; i != 0; i--)
+ fail |= ((i > AES_BLOCKSIZE - padsize) & (*out-- != padsize));
+
+ written -= padsize;
+ }
+ return written * !fail;
+}
+
+AES256CBCEncrypt::AES256CBCEncrypt(const unsigned char key[AES256_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn)
+ : enc(key), pad(padIn)
+{
+ memcpy(iv, ivIn, AES_BLOCKSIZE);
+}
+
+int AES256CBCEncrypt::Encrypt(const unsigned char* data, int size, unsigned char* out) const
+{
+ return CBCEncrypt(enc, iv, data, size, pad, out);
+}
+
+AES256CBCEncrypt::~AES256CBCEncrypt()
+{
+ memset(iv, 0, sizeof(iv));
+}
+
+AES256CBCDecrypt::AES256CBCDecrypt(const unsigned char key[AES256_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn)
+ : dec(key), pad(padIn)
+{
+ memcpy(iv, ivIn, AES_BLOCKSIZE);
+}
+
+
+int AES256CBCDecrypt::Decrypt(const unsigned char* data, int size, unsigned char* out) const
+{
+ return CBCDecrypt(dec, iv, data, size, pad, out);
+}
+
+AES256CBCDecrypt::~AES256CBCDecrypt()
+{
+ memset(iv, 0, sizeof(iv));
+}
+
+AES128CBCEncrypt::AES128CBCEncrypt(const unsigned char key[AES128_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn)
+ : enc(key), pad(padIn)
+{
+ memcpy(iv, ivIn, AES_BLOCKSIZE);
+}
+
+AES128CBCEncrypt::~AES128CBCEncrypt()
+{
+ memset(iv, 0, AES_BLOCKSIZE);
+}
+
+int AES128CBCEncrypt::Encrypt(const unsigned char* data, int size, unsigned char* out) const
+{
+ return CBCEncrypt(enc, iv, data, size, pad, out);
+}
+
+AES128CBCDecrypt::AES128CBCDecrypt(const unsigned char key[AES128_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn)
+ : dec(key), pad(padIn)
+{
+ memcpy(iv, ivIn, AES_BLOCKSIZE);
+}
+
+AES128CBCDecrypt::~AES128CBCDecrypt()
+{
+ memset(iv, 0, AES_BLOCKSIZE);
+}
+
+int AES128CBCDecrypt::Decrypt(const unsigned char* data, int size, unsigned char* out) const
+{
+ return CBCDecrypt(dec, iv, data, size, pad, out);
+}
diff --git a/src/crypto/aes.h b/src/crypto/aes.h
index 4bf17a33ea..8cae357c12 100644
--- a/src/crypto/aes.h
+++ b/src/crypto/aes.h
@@ -63,4 +63,56 @@ public:
void Decrypt(unsigned char plaintext[16], const unsigned char ciphertext[16]) const;
};
+class AES256CBCEncrypt
+{
+public:
+ AES256CBCEncrypt(const unsigned char key[AES256_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn);
+ ~AES256CBCEncrypt();
+ int Encrypt(const unsigned char* data, int size, unsigned char* out) const;
+
+private:
+ const AES256Encrypt enc;
+ const bool pad;
+ unsigned char iv[AES_BLOCKSIZE];
+};
+
+class AES256CBCDecrypt
+{
+public:
+ AES256CBCDecrypt(const unsigned char key[AES256_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn);
+ ~AES256CBCDecrypt();
+ int Decrypt(const unsigned char* data, int size, unsigned char* out) const;
+
+private:
+ const AES256Decrypt dec;
+ const bool pad;
+ unsigned char iv[AES_BLOCKSIZE];
+};
+
+class AES128CBCEncrypt
+{
+public:
+ AES128CBCEncrypt(const unsigned char key[AES128_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn);
+ ~AES128CBCEncrypt();
+ int Encrypt(const unsigned char* data, int size, unsigned char* out) const;
+
+private:
+ const AES128Encrypt enc;
+ const bool pad;
+ unsigned char iv[AES_BLOCKSIZE];
+};
+
+class AES128CBCDecrypt
+{
+public:
+ AES128CBCDecrypt(const unsigned char key[AES128_KEYSIZE], const unsigned char ivIn[AES_BLOCKSIZE], bool padIn);
+ ~AES128CBCDecrypt();
+ int Decrypt(const unsigned char* data, int size, unsigned char* out) const;
+
+private:
+ const AES128Decrypt dec;
+ const bool pad;
+ unsigned char iv[AES_BLOCKSIZE];
+};
+
#endif // BITCOIN_CRYPTO_AES_H