/**
* scryptdec_buf(inbuf, inbuflen, outbuf, outlen, passwd, passwdlen,
* maxmem, maxmemfrac, maxtime):
* Decrypt inbuflen bytes from inbuf, writing the result into outbuf and the
* decrypted data length to outlen. The allocated length of outbuf must
* be at least inbuflen.
*/
int
scryptdec_buf(const uint8_t * inbuf, size_t inbuflen, uint8_t * outbuf,
size_t * outlen, const uint8_t * passwd, size_t passwdlen,
size_t maxmem, double maxmemfrac, double maxtime)
{
uint8_t hbuf[32];
uint8_t dk[64];
uint8_t * key_enc = dk;
uint8_t * key_hmac = &dk[32];
int rc;
HMAC_SHA256_CTX hctx;
struct crypto_aes_key * key_enc_exp;
struct crypto_aesctr * AES;
/*
* All versions of the scrypt format will start with "scrypt" and
* have at least 7 bytes of header.
*/
if ((inbuflen < 7) || (memcmp(inbuf, "scrypt", 6) != 0))
return (7);
/* Check the format. */
if (inbuf[6] != 0)
return (8);
/* We must have at least 128 bytes. */
if (inbuflen < 128)
return (7);
/* Parse the header and generate derived keys. */
if ((rc = scryptdec_setup(inbuf, dk, passwd, passwdlen,
maxmem, maxmemfrac, maxtime)) != 0)
return (rc);
/* Decrypt data. */
if ((key_enc_exp = crypto_aes_key_expand(key_enc, 32)) == NULL)
return (5);
if ((AES = crypto_aesctr_init(key_enc_exp, 0)) == NULL)
return (6);
crypto_aesctr_stream(AES, &inbuf[96], outbuf, inbuflen - 128);
crypto_aesctr_free(AES);
crypto_aes_key_free(key_enc_exp);
*outlen = inbuflen - 128;
/* Verify signature. */
HMAC_SHA256_Init(&hctx, key_hmac, 32);
HMAC_SHA256_Update(&hctx, inbuf, inbuflen - 32);
HMAC_SHA256_Final(hbuf, &hctx);
if (memcmp(hbuf, &inbuf[inbuflen - 32], 32))
return (7);
/* Zero sensitive data. */
insecure_memzero(dk, 64);
/* Success! */
return (0);
}
/**
* scryptenc_buf(inbuf, inbuflen, outbuf, passwd, passwdlen,
* maxmem, maxmemfrac, maxtime):
* Encrypt inbuflen bytes from inbuf, writing the resulting inbuflen + 128
* bytes to outbuf.
*/
int
scryptenc_buf(const uint8_t * inbuf, size_t inbuflen, uint8_t * outbuf,
const uint8_t * passwd, size_t passwdlen,
size_t maxmem, double maxmemfrac, double maxtime)
{
uint8_t dk[64];
uint8_t hbuf[32];
uint8_t header[96];
uint8_t * key_enc = dk;
uint8_t * key_hmac = &dk[32];
int rc;
HMAC_SHA256_CTX hctx;
struct crypto_aes_key * key_enc_exp;
struct crypto_aesctr * AES;
/* Generate the header and derived key. */
if ((rc = scryptenc_setup(header, dk, passwd, passwdlen,
maxmem, maxmemfrac, maxtime)) != 0)
return (rc);
/* Copy header into output buffer. */
memcpy(outbuf, header, 96);
/* Encrypt data. */
if ((key_enc_exp = crypto_aes_key_expand(key_enc, 32)) == NULL)
return (5);
if ((AES = crypto_aesctr_init(key_enc_exp, 0)) == NULL)
return (6);
crypto_aesctr_stream(AES, inbuf, &outbuf[96], inbuflen);
crypto_aesctr_free(AES);
crypto_aes_key_free(key_enc_exp);
/* Add signature. */
HMAC_SHA256_Init(&hctx, key_hmac, 32);
HMAC_SHA256_Update(&hctx, outbuf, 96 + inbuflen);
HMAC_SHA256_Final(hbuf, &hctx);
memcpy(&outbuf[96 + inbuflen], hbuf, 32);
/* Zero sensitive data. */
insecure_memzero(dk, 64);
/* Success! */
return (0);
}
/**
* scryptdec_file(infile, outfile, passwd, passwdlen,
* maxmem, maxmemfrac, maxtime):
* Read a stream from infile and decrypt it, writing the resulting stream to
* outfile.
*/
int
scryptdec_file(FILE * infile, FILE * outfile,
const uint8_t * passwd, size_t passwdlen,
size_t maxmem, double maxmemfrac, double maxtime)
{
uint8_t buf[ENCBLOCK + 32];
uint8_t header[96];
uint8_t hbuf[32];
uint8_t dk[64];
uint8_t * key_enc = dk;
uint8_t * key_hmac = &dk[32];
size_t buflen = 0;
size_t readlen;
HMAC_SHA256_CTX hctx;
struct crypto_aes_key * key_enc_exp;
struct crypto_aesctr * AES;
int rc;
/*
* Read the first 7 bytes of the file; all future versions of scrypt
* are guaranteed to have at least 7 bytes of header.
*/
if (fread(header, 7, 1, infile) < 1) {
if (ferror(infile))
return (13);
else
return (7);
}
/* Do we have the right magic? */
if (memcmp(header, "scrypt", 6))
return (7);
if (header[6] != 0)
return (8);
/*
* Read another 89 bytes of the file; version 0 of the scrypt file
* format has a 96-byte header.
*/
if (fread(&header[7], 89, 1, infile) < 1) {
if (ferror(infile))
return (13);
else
return (7);
}
/* Parse the header and generate derived keys. */
if ((rc = scryptdec_setup(header, dk, passwd, passwdlen,
maxmem, maxmemfrac, maxtime)) != 0)
return (rc);
/* Start hashing with the header. */
HMAC_SHA256_Init(&hctx, key_hmac, 32);
HMAC_SHA256_Update(&hctx, header, 96);
/*
* We don't know how long the encrypted data block is (we can't know,
* since data can be streamed into 'scrypt enc') so we need to read
* data and decrypt all of it except the final 32 bytes, then check
* if that final 32 bytes is the correct signature.
*/
if ((key_enc_exp = crypto_aes_key_expand(key_enc, 32)) == NULL)
return (5);
if ((AES = crypto_aesctr_init(key_enc_exp, 0)) == NULL)
return (6);
do {
/* Read data until we have more than 32 bytes of it. */
if ((readlen = fread(&buf[buflen], 1,
ENCBLOCK + 32 - buflen, infile)) == 0)
break;
buflen += readlen;
if (buflen <= 32)
continue;
/*
* Decrypt, hash, and output everything except the last 32
* bytes out of what we have in our buffer.
*/
HMAC_SHA256_Update(&hctx, buf, buflen - 32);
crypto_aesctr_stream(AES, buf, buf, buflen - 32);
if (fwrite(buf, 1, buflen - 32, outfile) < buflen - 32) {
crypto_aesctr_free(AES);
return (12);
}
/* Move the last 32 bytes to the start of the buffer. */
memmove(buf, &buf[buflen - 32], 32);
buflen = 32;
} while (1);
crypto_aesctr_free(AES);
crypto_aes_key_free(key_enc_exp);
/* Did we exit the loop due to a read error? */
if (ferror(infile))
return (13);
/* Did we read enough data that we *might* have a valid signature? */
if (buflen < 32)
return (7);
/* Verify signature. */
HMAC_SHA256_Final(hbuf, &hctx);
if (memcmp(hbuf, buf, 32))
return (7);
/* Zero sensitive data. */
insecure_memzero(dk, 64);
return (0);
}
/**
* scryptenc_file(infile, outfile, passwd, passwdlen,
* maxmem, maxmemfrac, maxtime):
* Read a stream from infile and encrypt it, writing the resulting stream to
* outfile.
*/
int
scryptenc_file(FILE * infile, FILE * outfile,
const uint8_t * passwd, size_t passwdlen,
size_t maxmem, double maxmemfrac, double maxtime)
{
uint8_t buf[ENCBLOCK];
uint8_t dk[64];
uint8_t hbuf[32];
uint8_t header[96];
uint8_t * key_enc = dk;
uint8_t * key_hmac = &dk[32];
size_t readlen;
HMAC_SHA256_CTX hctx;
struct crypto_aes_key * key_enc_exp;
struct crypto_aesctr * AES;
int rc;
/* Generate the header and derived key. */
if ((rc = scryptenc_setup(header, dk, passwd, passwdlen,
maxmem, maxmemfrac, maxtime)) != 0)
return (rc);
/* Hash and write the header. */
HMAC_SHA256_Init(&hctx, key_hmac, 32);
HMAC_SHA256_Update(&hctx, header, 96);
if (fwrite(header, 96, 1, outfile) != 1)
return (12);
/*
* Read blocks of data, encrypt them, and write them out; hash the
* data as it is produced.
*/
if ((key_enc_exp = crypto_aes_key_expand(key_enc, 32)) == NULL)
return (5);
if ((AES = crypto_aesctr_init(key_enc_exp, 0)) == NULL)
return (6);
do {
if ((readlen = fread(buf, 1, ENCBLOCK, infile)) == 0)
break;
crypto_aesctr_stream(AES, buf, buf, readlen);
HMAC_SHA256_Update(&hctx, buf, readlen);
if (fwrite(buf, 1, readlen, outfile) < readlen) {
crypto_aesctr_free(AES);
return (12);
}
} while (1);
crypto_aesctr_free(AES);
crypto_aes_key_free(key_enc_exp);
/* Did we exit the loop due to a read error? */
if (ferror(infile))
return (13);
/* Compute the final HMAC and output it. */
HMAC_SHA256_Final(hbuf, &hctx);
if (fwrite(hbuf, 32, 1, outfile) != 1)
return (12);
/* Zero sensitive data. */
insecure_memzero(dk, 64);
/* Success! */
return (0);
}
/**
* crypto_session_init(pub, priv, nonce, mkey, encr_write, auth_write,
* encr_read, auth_read):
* Compute K = ${pub}^(2^258 + ${priv}), mkey = MGF1(nonce || K, 48), and
* return a CRYPTO_SESSION with encryption and authentication write and read
* keys constructed from HMAC(mkey, (encr|auth)_(write|read)).
*/
CRYPTO_SESSION *
crypto_session_init(uint8_t pub[CRYPTO_DH_PUBLEN],
uint8_t priv[CRYPTO_DH_PRIVLEN], uint8_t nonce[32], uint8_t mkey[48],
const char * encr_write, const char * auth_write,
const char * encr_read, const char * auth_read)
{
struct crypto_session_internal * CS;
uint8_t K[CRYPTO_DH_PUBLEN];
uint8_t MGFbuf[32 + CRYPTO_DH_PUBLEN];
uint8_t aes_write[32];
uint8_t aes_read[32];
/* Compute K = 2^(xy) mod p. */
if (crypto_dh_compute(pub, priv, K))
goto err0;
/* Shared key is MGF1(nonce || K, 48). */
memcpy(MGFbuf, nonce, 32);
memcpy(MGFbuf + 32, K, CRYPTO_DH_PUBLEN);
crypto_MGF1(MGFbuf, 32 + CRYPTO_DH_PUBLEN, mkey, 48);
/* Allocate space for session key structure. */
if ((CS = malloc(sizeof(struct crypto_session_internal))) == NULL)
goto err0;
/* Generate raw keys. */
crypto_hash_data_key(mkey, 48,
(const uint8_t *)encr_write, strlen(encr_write), aes_write);
crypto_hash_data_key(mkey, 48,
(const uint8_t *)auth_write, strlen(auth_write), CS->auth_write);
crypto_hash_data_key(mkey, 48,
(const uint8_t *)encr_read, strlen(encr_read), aes_read);
crypto_hash_data_key(mkey, 48,
(const uint8_t *)auth_read, strlen(auth_read), CS->auth_read);
/* Expand AES keys and set up streams. */
if (AES_set_encrypt_key(aes_write, 256, &CS->encr_write)) {
warn0("error in AES_set_encrypt_key");
goto err1;
}
if (AES_set_encrypt_key(aes_read, 256, &CS->encr_read)) {
warn0("error in AES_set_encrypt_key");
goto err1;
}
if ((CS->encr_write_stream =
crypto_aesctr_init(&CS->encr_write, 0)) == NULL)
goto err1;
if ((CS->encr_read_stream =
crypto_aesctr_init(&CS->encr_read, 0)) == NULL)
goto err2;
/* Initialize parameters. */
CS->auth_write_nonce = CS->auth_read_nonce = 0;
/* Success! */
return (CS);
err2:
crypto_aesctr_free(CS->encr_write_stream);
err1:
free(CS);
err0:
/* Failure! */
return (NULL);
}
