aboutsummaryrefslogtreecommitdiffstats
path: root/crypto/ec/curve448/ed448.h
diff options
context:
space:
mode:
Diffstat (limited to 'crypto/ec/curve448/ed448.h')
-rw-r--r--crypto/ec/curve448/ed448.h195
1 files changed, 195 insertions, 0 deletions
diff --git a/crypto/ec/curve448/ed448.h b/crypto/ec/curve448/ed448.h
new file mode 100644
index 000000000000..5fe939e8e19d
--- /dev/null
+++ b/crypto/ec/curve448/ed448.h
@@ -0,0 +1,195 @@
+/*
+ * Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2015-2016 Cryptography Research, Inc.
+ *
+ * Licensed under the OpenSSL license (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ *
+ * Originally written by Mike Hamburg
+ */
+
+#ifndef HEADER_ED448_H
+# define HEADER_ED448_H
+
+# include "point_448.h"
+
+/* Number of bytes in an EdDSA public key. */
+# define EDDSA_448_PUBLIC_BYTES 57
+
+/* Number of bytes in an EdDSA private key. */
+# define EDDSA_448_PRIVATE_BYTES EDDSA_448_PUBLIC_BYTES
+
+/* Number of bytes in an EdDSA private key. */
+# define EDDSA_448_SIGNATURE_BYTES (EDDSA_448_PUBLIC_BYTES + \
+ EDDSA_448_PRIVATE_BYTES)
+
+/* EdDSA encoding ratio. */
+# define C448_EDDSA_ENCODE_RATIO 4
+
+/* EdDSA decoding ratio. */
+# define C448_EDDSA_DECODE_RATIO (4 / 4)
+
+/*
+ * EdDSA key generation. This function uses a different (non-Decaf) encoding.
+ *
+ * pubkey (out): The public key.
+ * privkey (in): The private key.
+ */
+c448_error_t c448_ed448_derive_public_key(
+ uint8_t pubkey [EDDSA_448_PUBLIC_BYTES],
+ const uint8_t privkey [EDDSA_448_PRIVATE_BYTES]);
+
+/*
+ * EdDSA signing.
+ *
+ * signature (out): The signature.
+ * privkey (in): The private key.
+ * pubkey (in): The public key.
+ * message (in): The message to sign.
+ * message_len (in): The length of the message.
+ * prehashed (in): Nonzero if the message is actually the hash of something
+ * you want to sign.
+ * context (in): A "context" for this signature of up to 255 bytes.
+ * context_len (in): Length of the context.
+ *
+ * For Ed25519, it is unsafe to use the same key for both prehashed and
+ * non-prehashed messages, at least without some very careful protocol-level
+ * disambiguation. For Ed448 it is safe.
+ */
+c448_error_t c448_ed448_sign(
+ uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
+ const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
+ const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+ const uint8_t *message, size_t message_len,
+ uint8_t prehashed, const uint8_t *context,
+ size_t context_len);
+
+/*
+ * EdDSA signing with prehash.
+ *
+ * signature (out): The signature.
+ * privkey (in): The private key.
+ * pubkey (in): The public key.
+ * hash (in): The hash of the message. This object will not be modified by the
+ * call.
+ * context (in): A "context" for this signature of up to 255 bytes. Must be the
+ * same as what was used for the prehash.
+ * context_len (in): Length of the context.
+ *
+ * For Ed25519, it is unsafe to use the same key for both prehashed and
+ * non-prehashed messages, at least without some very careful protocol-level
+ * disambiguation. For Ed448 it is safe.
+ */
+c448_error_t c448_ed448_sign_prehash(
+ uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
+ const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
+ const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+ const uint8_t hash[64],
+ const uint8_t *context,
+ size_t context_len);
+
+/*
+ * EdDSA signature verification.
+ *
+ * Uses the standard (i.e. less-strict) verification formula.
+ *
+ * signature (in): The signature.
+ * pubkey (in): The public key.
+ * message (in): The message to verify.
+ * message_len (in): The length of the message.
+ * prehashed (in): Nonzero if the message is actually the hash of something you
+ * want to verify.
+ * context (in): A "context" for this signature of up to 255 bytes.
+ * context_len (in): Length of the context.
+ *
+ * For Ed25519, it is unsafe to use the same key for both prehashed and
+ * non-prehashed messages, at least without some very careful protocol-level
+ * disambiguation. For Ed448 it is safe.
+ */
+c448_error_t c448_ed448_verify(const uint8_t
+ signature[EDDSA_448_SIGNATURE_BYTES],
+ const uint8_t
+ pubkey[EDDSA_448_PUBLIC_BYTES],
+ const uint8_t *message, size_t message_len,
+ uint8_t prehashed, const uint8_t *context,
+ uint8_t context_len);
+
+/*
+ * EdDSA signature verification.
+ *
+ * Uses the standard (i.e. less-strict) verification formula.
+ *
+ * signature (in): The signature.
+ * pubkey (in): The public key.
+ * hash (in): The hash of the message. This object will not be modified by the
+ * call.
+ * context (in): A "context" for this signature of up to 255 bytes. Must be the
+ * same as what was used for the prehash.
+ * context_len (in): Length of the context.
+ *
+ * For Ed25519, it is unsafe to use the same key for both prehashed and
+ * non-prehashed messages, at least without some very careful protocol-level
+ * disambiguation. For Ed448 it is safe.
+ */
+c448_error_t c448_ed448_verify_prehash(
+ const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
+ const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+ const uint8_t hash[64],
+ const uint8_t *context,
+ uint8_t context_len);
+
+/*
+ * EdDSA point encoding. Used internally, exposed externally.
+ * Multiplies by C448_EDDSA_ENCODE_RATIO first.
+ *
+ * The multiplication is required because the EdDSA encoding represents
+ * the cofactor information, but the Decaf encoding ignores it (which
+ * is the whole point). So if you decode from EdDSA and re-encode to
+ * EdDSA, the cofactor info must get cleared, because the intermediate
+ * representation doesn't track it.
+ *
+ * The way we handle this is to multiply by C448_EDDSA_DECODE_RATIO when
+ * decoding, and by C448_EDDSA_ENCODE_RATIO when encoding. The product of
+ * these ratios is always exactly the cofactor 4, so the cofactor ends up
+ * cleared one way or another. But exactly how that shakes out depends on the
+ * base points specified in RFC 8032.
+ *
+ * The upshot is that if you pass the Decaf/Ristretto base point to
+ * this function, you will get C448_EDDSA_ENCODE_RATIO times the
+ * EdDSA base point.
+ *
+ * enc (out): The encoded point.
+ * p (in): The point.
+ */
+void curve448_point_mul_by_ratio_and_encode_like_eddsa(
+ uint8_t enc [EDDSA_448_PUBLIC_BYTES],
+ const curve448_point_t p);
+
+/*
+ * EdDSA point decoding. Multiplies by C448_EDDSA_DECODE_RATIO, and
+ * ignores cofactor information.
+ *
+ * See notes on curve448_point_mul_by_ratio_and_encode_like_eddsa
+ *
+ * enc (out): The encoded point.
+ * p (in): The point.
+ */
+c448_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio(
+ curve448_point_t p,
+ const uint8_t enc[EDDSA_448_PUBLIC_BYTES]);
+
+/*
+ * EdDSA to ECDH private key conversion
+ * Using the appropriate hash function, hash the EdDSA private key
+ * and keep only the lower bytes to get the ECDH private key
+ *
+ * x (out): The ECDH private key as in RFC7748
+ * ed (in): The EdDSA private key
+ */
+c448_error_t c448_ed448_convert_private_key_to_x448(
+ uint8_t x[X448_PRIVATE_BYTES],
+ const uint8_t ed[EDDSA_448_PRIVATE_BYTES]);
+
+#endif /* HEADER_ED448_H */