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-rw-r--r--Makefile.in2
-rw-r--r--aes_keywrap.c261
-rw-r--r--cryptech.h87
-rw-r--r--csprng.c4
-rw-r--r--hash.c2
5 files changed, 314 insertions, 42 deletions
diff --git a/Makefile.in b/Makefile.in
index b03924b..b984151 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -2,7 +2,7 @@
INC = cryptech.h
LIB = libcryptech.a
-OBJ = ${IO_OBJ} csprng.o hash.o
+OBJ = ${IO_OBJ} csprng.o hash.o aes_keywrap.o
IO_OBJ = ${IO_OBJ_@FPGA_BUS@}
IO_OBJ_EIM = hal_io_eim.o novena-eim.o
diff --git a/aes_keywrap.c b/aes_keywrap.c
new file mode 100644
index 0000000..b8f505f
--- /dev/null
+++ b/aes_keywrap.c
@@ -0,0 +1,261 @@
+/*
+ * Implementation of RFC 5649 variant of AES Key Wrap, using Cryptlib
+ * to supply the AES ECB encryption and decryption functions.
+ *
+ * Note that there are two different block sizes involved here: the
+ * key wrap algorithm deals entirely with 64-bit blocks, while AES
+ * itself deals with 128-bit blocks. In practice, this is not as
+ * confusing as it sounds, because we combine two 64-bit blocks to
+ * create one 128-bit block just prior to performing an AES operation,
+ * then split the result back to 64-bit blocks immediately afterwards.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <assert.h>
+
+#include "cryptech.h"
+
+
+/*
+ * How long the ciphertext will be for a given plaintext length.
+ */
+
+size_t hal_aes_keywrap_ciphertext_length(const size_t plaintext_length)
+{
+ return (plaintext_length + 15) & ~7;
+}
+
+
+/*
+ * Check the KEK, then load it into the AES core.
+ * Note that our AES core only supports 128 and 256 bit keys.
+ */
+
+typedef enum { KEK_encrypting, KEK_decrypting } kek_action_t;
+
+static hal_error_t load_kek(const uint8_t *K, const size_t K_len, const kek_action_t action)
+{
+ uint8_t config[4];
+ hal_error_t err;
+
+ if (K == NULL)
+ return HAL_ERROR_BAD_ARGUMENTS;
+
+ memset(config, 0, sizeof(config));
+
+ switch (K_len) {
+ case bitsToBytes(128):
+ config[3] &= ~AES_CONFIG_KEYLEN;
+ break;
+ case bitsToBytes(256):
+ config[3] |= AES_CONFIG_KEYLEN;
+ break;
+ default:
+ return HAL_ERROR_BAD_ARGUMENTS;
+ }
+
+ switch (action) {
+ case KEK_encrypting:
+ config[3] |= AES_CONFIG_ENCDEC;
+ break;
+ case KEK_decrypting:
+ config[3] &= !AES_CONFIG_ENCDEC;
+ break;
+ default:
+ return HAL_ERROR_BAD_ARGUMENTS;
+ }
+
+ /*
+ * Load the KEK and tell the core to expand it.
+ */
+
+ if ((err = hal_io_write(AES_ADDR_KEY0, K, K_len)) != HAL_OK ||
+ (err = hal_io_init(AES_ADDR_CTRL)) != HAL_OK)
+ return err;
+
+ return HAL_OK;
+}
+
+
+/*
+ * Process one block. Since AES Key Wrap always deals with 64-bit
+ * half blocks and since the bus is going to break this up into 32-bit
+ * words no matter what we do, we can eliminate a few gratuitous
+ * memcpy() operations by receiving our arguments as two half blocks.
+ *
+ * Since the length of these half blocks is constant, there's no real
+ * point in passing the length as an argument, we'd just be checking a
+ * constant against a constant and a smart compiler will optimize
+ * the whole check out.
+ *
+ * Just be VERY careful if you change anything here.
+ */
+
+static hal_error_t do_block(uint8_t *b1, uint8_t *b2)
+{
+ hal_error_t err;
+
+ assert(b1 != NULL && b2 != NULL);
+
+ if ((err = hal_io_write(AES_ADDR_BLOCK0, b1, 8)) != HAL_OK ||
+ (err = hal_io_write(AES_ADDR_BLOCK2, b2, 8)) != HAL_OK ||
+ (err = hal_io_next(AES_ADDR_CTRL)) != HAL_OK ||
+ (err = hal_io_wait_ready(AES_ADDR_STATUS)) != HAL_OK ||
+ (err = hal_io_read(AES_ADDR_RESULT0, b1, 8)) != HAL_OK ||
+ (err = hal_io_read(AES_ADDR_RESULT2, b2, 8)) != HAL_OK)
+ return err;
+
+ return HAL_OK;
+}
+
+
+/*
+ * Wrap plaintext Q using KEK K, placing result in C.
+ *
+ * Q and C can overlap. For encrypt-in-place, use Q = C + 8 (that is,
+ * leave 8 empty bytes before the plaintext).
+ *
+ * Use hal_aes_keywrap_ciphertext_length() to calculate the correct
+ * buffer size.
+ */
+
+hal_error_t hal_aes_keywrap(const uint8_t *K, const size_t K_len,
+ const uint8_t * const Q,
+ const size_t m,
+ uint8_t *C,
+ size_t *C_len)
+{
+ const size_t calculated_C_len = hal_aes_keywrap_ciphertext_length(m);
+ hal_error_t err;
+ uint32_t n;
+ long i, j;
+
+ assert(calculated_C_len % 8 == 0);
+
+ if (Q == NULL || C == NULL || C_len == NULL || *C_len < calculated_C_len)
+ return HAL_ERROR_BAD_ARGUMENTS;
+
+ if ((err = load_kek(K, K_len, KEK_encrypting)) != HAL_OK)
+ return err;
+
+ *C_len = calculated_C_len;
+
+ if (C + 8 != Q)
+ memmove(C + 8, Q, m);
+ if (m % 8 != 0)
+ memset(C + 8 + m, 0, 8 - (m % 8));
+ C[0] = 0xA6;
+ C[1] = 0x59;
+ C[2] = 0x59;
+ C[3] = 0xA6;
+ C[4] = (m >> 24) & 0xFF;
+ C[5] = (m >> 16) & 0xFF;
+ C[6] = (m >> 8) & 0xFF;
+ C[7] = (m >> 0) & 0xFF;
+
+ n = calculated_C_len/8 - 1;
+
+ if (n == 1) {
+ if ((err = do_block(C, C + 8)) != HAL_OK)
+ return err;
+ }
+
+ else {
+ for (j = 0; j <= 5; j++) {
+ for (i = 1; i <= n; i++) {
+ uint32_t t = n * j + i;
+ if ((err = do_block(C, C + i * 8)) != HAL_OK)
+ return err;
+ C[7] ^= t & 0xFF; t >>= 8;
+ C[6] ^= t & 0xFF; t >>= 8;
+ C[5] ^= t & 0xFF; t >>= 8;
+ C[4] ^= t & 0xFF;
+ }
+ }
+ }
+
+ return HAL_OK;
+}
+
+
+/*
+ * Unwrap ciphertext C using KEK K, placing result in Q.
+ *
+ * Q should be the same size as C. Q and C can overlap.
+ */
+
+hal_error_t hal_aes_keyunwrap(const uint8_t *K, const size_t K_len,
+ const uint8_t * const C,
+ const size_t C_len,
+ uint8_t *Q,
+ size_t *Q_len)
+{
+ hal_error_t err;
+ uint32_t n;
+ long i, j;
+ size_t m;
+
+ if (C == NULL || Q == NULL || C_len % 8 != 0 || C_len < 16 || Q_len == NULL || *Q_len < C_len)
+ return HAL_ERROR_BAD_ARGUMENTS;
+
+ if ((err = load_kek(K, K_len, KEK_decrypting)) != HAL_OK)
+ return err;
+
+ n = (C_len / 8) - 1;
+
+ if (Q != C)
+ memmove(Q, C, C_len);
+
+ if (n == 1) {
+ if ((err = do_block(Q, Q + 8)) != HAL_OK)
+ return err;
+ }
+
+ else {
+ for (j = 5; j >= 0; j--) {
+ for (i = n; i >= 1; i--) {
+ uint32_t t = n * j + i;
+ Q[7] ^= t & 0xFF; t >>= 8;
+ Q[6] ^= t & 0xFF; t >>= 8;
+ Q[5] ^= t & 0xFF; t >>= 8;
+ Q[4] ^= t & 0xFF;
+ if ((err = do_block(Q, Q + i * 8)) != HAL_OK)
+ return err;
+ }
+ }
+ }
+
+ if (Q[0] != 0xA6 || Q[1] != 0x59 || Q[2] != 0x59 || Q[3] != 0xA6)
+ return HAL_ERROR_KEYWRAP_BAD_MAGIC;
+
+ m = (((((Q[4] << 8) + Q[5]) << 8) + Q[6]) << 8) + Q[7];
+
+ if (m <= 8 * (n - 1) || m > 8 * n)
+ return HAL_ERROR_KEYWRAP_BAD_LENGTH;
+
+ if (m % 8 != 0)
+ for (i = m + 8; i < 8 * (n + 1); i++)
+ if (Q[i] != 0x00)
+ return HAL_ERROR_KEYWRAP_BAD_PADDING;
+
+ *Q_len = m;
+
+ memmove(Q, Q + 8, m);
+
+ return HAL_OK;
+}
+
+/*
+ * "Any programmer who fails to comply with the standard naming, formatting,
+ * or commenting conventions should be shot. If it so happens that it is
+ * inconvenient to shoot him, then he is to be politely requested to recode
+ * his program in adherence to the above standard."
+ * -- Michael Spier, Digital Equipment Corporation
+ *
+ * Local variables:
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/cryptech.h b/cryptech.h
index 903fbd4..dce2b8b 100644
--- a/cryptech.h
+++ b/cryptech.h
@@ -429,15 +429,18 @@
*/
typedef enum {
- HAL_OK, /* All's well */
- HAL_ERROR_MEMORY, /* malloc() failure or similar */
- HAL_ERROR_INCONSISTENT_ARGS, /* Inconsistent arguments given */
- HAL_ERROR_IO_SETUP_FAILED, /* Could not set up I/O with FPGA */
- HAL_ERROR_IO_TIMEOUT, /* I/O with FPGA timed out */
- HAL_ERROR_IO_UNEXPECTED, /* Unexpected response from FPGA */
- HAL_ERROR_IO_OS_ERROR, /* Operating system error talking to FPGA */
- HAL_ERROR_CSPRNG_ZEROED, /* CSPRNG is returning zeros (perhaps core not present?) */
- N_HAL_ERRORS /* Number of error codes (must be last) */
+ HAL_OK, /* All's well */
+ HAL_ERROR_MEMORY, /* malloc() failure or similar */
+ HAL_ERROR_BAD_ARGUMENTS, /* Bad arguments given */
+ HAL_ERROR_IO_SETUP_FAILED, /* Could not set up I/O with FPGA */
+ HAL_ERROR_IO_TIMEOUT, /* I/O with FPGA timed out */
+ HAL_ERROR_IO_UNEXPECTED, /* Unexpected response from FPGA */
+ HAL_ERROR_IO_OS_ERROR, /* Operating system error talking to FPGA */
+ HAL_ERROR_CSPRNG_BROKEN, /* CSPRNG is returning nonsense (perhaps core not present?) */
+ HAL_ERROR_KEYWRAP_BAD_MAGIC, /* Bad magic number while unwrapping key */
+ HAL_ERROR_KEYWRAP_BAD_LENGTH, /* Length out of range while unwrapping key */
+ HAL_ERROR_KEYWRAP_BAD_PADDING, /* Nonzero padding detected while unwrapping key */
+ N_HAL_ERRORS /* Number of error codes (must be last) */
} hal_error_t;
@@ -449,39 +452,47 @@ typedef enum {
* Public I/O functions.
*/
-void hal_io_set_debug(int onoff);
-hal_error_t hal_io_write(off_t offset, const uint8_t *buf, size_t len);
-hal_error_t hal_io_read(off_t offset, uint8_t *buf, size_t len);
-hal_error_t hal_io_expected(off_t offset, const uint8_t *expected, size_t len);
-hal_error_t hal_io_init(off_t offset);
-hal_error_t hal_io_next(off_t offset);
-hal_error_t hal_io_wait(off_t offset, uint8_t status, int *count);
-hal_error_t hal_io_wait_ready(off_t offset);
-hal_error_t hal_io_wait_valid(off_t offset);
+extern void hal_io_set_debug(int onoff);
+extern hal_error_t hal_io_write(off_t offset, const uint8_t *buf, size_t len);
+extern hal_error_t hal_io_read(off_t offset, uint8_t *buf, size_t len);
+extern hal_error_t hal_io_expected(off_t offset, const uint8_t *expected, size_t len);
+extern hal_error_t hal_io_init(off_t offset);
+extern hal_error_t hal_io_next(off_t offset);
+extern hal_error_t hal_io_wait(off_t offset, uint8_t status, int *count);
+extern hal_error_t hal_io_wait_ready(off_t offset);
+extern hal_error_t hal_io_wait_valid(off_t offset);
/*
* Higher level public API.
*/
-hal_error_t hal_random(void *buffer, const size_t length);
-
-void hal_hash_set_debug(int onoff);
-hal_error_t hash_sha1_core_present(void);
-hal_error_t hash_sha256_core_present(void);
-hal_error_t hash_sha512_core_present(void);
-size_t hal_hash_state_size(void);
-void hal_hash_state_initialize(void *state);
-hal_error_t hal_hash_sha1(void *state, const uint8_t * data_buffer, const size_t data_buffer_length,
- uint8_t *digest_buffer, const size_t digest_buffer_length);
-hal_error_t hal_hash_sha256(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
- uint8_t *digest_buffer, const size_t digest_buffer_length);
-hal_error_t hal_hash_sha512_224(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
- uint8_t *digest_buffer, const size_t digest_buffer_length);
-hal_error_t hal_hash_sha512_256(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
- uint8_t *digest_buffer, const size_t digest_buffer_length);
-hal_error_t hal_hash_sha384(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
- uint8_t *digest_buffer, const size_t digest_buffer_length);
-hal_error_t hal_hash_sha512(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
- uint8_t *digest_buffer, const size_t digest_buffer_length);
+extern hal_error_t hal_get_random(void *buffer, const size_t length);
+
+extern void hal_hash_set_debug(int onoff);
+extern hal_error_t hash_sha1_core_present(void);
+extern hal_error_t hash_sha256_core_present(void);
+extern hal_error_t hash_sha512_core_present(void);
+extern size_t hal_hash_state_size(void);
+extern void hal_hash_state_initialize(void *state);
+extern hal_error_t hal_hash_sha1(void *state, const uint8_t * data_buffer, const size_t data_buffer_length,
+ uint8_t *digest_buffer, const size_t digest_buffer_length);
+extern hal_error_t hal_hash_sha256(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
+ uint8_t *digest_buffer, const size_t digest_buffer_length);
+extern hal_error_t hal_hash_sha512_224(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
+ uint8_t *digest_buffer, const size_t digest_buffer_length);
+extern hal_error_t hal_hash_sha512_256(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
+ uint8_t *digest_buffer, const size_t digest_buffer_length);
+extern hal_error_t hal_hash_sha384(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
+ uint8_t *digest_buffer, const size_t digest_buffer_length);
+extern hal_error_t hal_hash_sha512(void *state, const uint8_t *data_buffer, const size_t data_buffer_length,
+ uint8_t *digest_buffer, const size_t digest_buffer_length);
+
+extern hal_error_t hal_aes_keywrap(const uint8_t *kek, const size_t kek_length,
+ const uint8_t *plaintext, const size_t plaintext_length,
+ uint8_t *cyphertext, size_t *ciphertext_length);
+extern hal_error_t hal_aes_keyunwrap(const uint8_t *kek, const size_t kek_length,
+ const uint8_t *ciphertext, const size_t ciphertext_length,
+ unsigned char *plaintext, size_t *plaintext_length);
+extern size_t hal_aes_keywrap_ciphertext_length(const size_t plaintext_length);
#endif /* _CRYPTECH_H_ */
diff --git a/csprng.c b/csprng.c
index f4f835d..becd3f7 100644
--- a/csprng.c
+++ b/csprng.c
@@ -53,7 +53,7 @@
#define WAIT_FOR_CSPRNG_VALID 1
#endif
-hal_error_t hal_random(void *buffer, const size_t length)
+hal_error_t hal_get_random(void *buffer, const size_t length)
{
uint8_t temp[4], *buf = buffer;
hal_error_t err;
@@ -77,7 +77,7 @@ hal_error_t hal_random(void *buffer, const size_t length)
if (*buf != 0)
return HAL_OK;
- return HAL_ERROR_CSPRNG_ZEROED;
+ return HAL_ERROR_CSPRNG_BROKEN;
}
/*
diff --git a/hash.c b/hash.c
index e41bf20..4a15491 100644
--- a/hash.c
+++ b/hash.c
@@ -191,7 +191,7 @@ static hal_error_t hash_do_hash(hash_state_t *state, /* Opaqu
(data_buffer_length > 0 && data_buffer == NULL) ||
(data_buffer_length == 0 && digest_buffer == NULL) ||
(digest_buffer != NULL && digest_buffer_length < digest_length))
- return HAL_ERROR_INCONSISTENT_ARGS;
+ return HAL_ERROR_BAD_ARGUMENTS;
if (state->block_length == 0)
state->block_length = block_length;