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Deprecate EdwardsPoint::hash_from_bytes (#438)

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* Deprecated `EdwardsPoint::hash_from_bytes` and renamed to
  `EdwardsPoint::nonspec_map_to_curve`

* Added KAT test vectors for `RistrettoPoint::from_uniform_bytes`
This commit is contained in:
Michael Rosenberg 2022-11-24 01:45:03 -05:00 committed by GitHub
parent f88cf6836b
commit 6eafb1ebda
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2 changed files with 185 additions and 6 deletions
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17
src/edwards.rs
View file

@ -534,10 +534,16 @@ impl EdwardsPoint {
CompressedEdwardsY(s)
}
/// Perform hashing to the group using the Elligator2 map
///
/// See https://tools.ietf.org/html/draft-irtf-cfrg-hash-to-curve-10#section-6.7.1
pub fn hash_from_bytes<D>(bytes: &[u8]) -> EdwardsPoint
/// Maps the digest of the input bytes to the curve. This is NOT a hash-to-curve function, as
/// it produces points with a non-uniform distribution. Rather, it performs something that
/// resembles (but is not) half of the
/// [`hash_to_curve`](https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-16.html#section-3-4.2.1)
/// function from the Elligator2 spec.
#[deprecated(
since = "4.0.0",
note = "previously named `hash_from_bytes`, this is not a secure hash function"
)]
pub fn nonspec_map_to_curve<D>(bytes: &[u8]) -> EdwardsPoint
where
D: Digest<OutputSize = U64> + Default,
{
@ -1719,13 +1725,14 @@ mod test {
}
#[test]
#[allow(deprecated)]
#[cfg(feature = "alloc")]
fn elligator_signal_test_vectors() {
for vector in test_vectors().iter() {
let input = hex::decode(vector[0]).unwrap();
let output = hex::decode(vector[1]).unwrap();
let point = EdwardsPoint::hash_from_bytes::<sha2::Sha512>(&input);
let point = EdwardsPoint::nonspec_map_to_curve::<sha2::Sha512>(&input);
assert_eq!(point.compress().to_bytes(), output[..]);
}
}

174
src/ristretto.rs
View file

@ -615,7 +615,9 @@ impl RistrettoPoint {
]
}
/// Computes the Ristretto Elligator map.
/// Computes the Ristretto Elligator map. This is the
/// [`MAP`](https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-04#section-4.3.4)
/// function defined in the Ristretto spec.
///
/// # Note
///
@ -748,6 +750,8 @@ impl RistrettoPoint {
/// takes the low 255 bits of each half mod p, applies the
/// Ristretto-flavored Elligator map to each, and adds the results.
pub fn from_uniform_bytes(bytes: &[u8; 64]) -> RistrettoPoint {
// This follows the one-way map construction from the Ristretto RFC:
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-04#section-4.3.4
let mut r_1_bytes = [0u8; 32];
r_1_bytes.copy_from_slice(&bytes[0..32]);
let r_1 = FieldElement::from_bytes(&r_1_bytes);
@ -1488,6 +1492,174 @@ mod test {
}
}
// Known answer tests for the one-way mapping function in the Ristretto RFC
#[test]
fn one_way_map() {
// These inputs are from
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-ristretto255-decaf448-04#appendix-A.3
let test_vectors: &[([u8; 64], CompressedRistretto)] = &[
(
[
0x5d, 0x1b, 0xe0, 0x9e, 0x3d, 0x0c, 0x82, 0xfc, 0x53, 0x81, 0x12, 0x49, 0x0e,
0x35, 0x70, 0x19, 0x79, 0xd9, 0x9e, 0x06, 0xca, 0x3e, 0x2b, 0x5b, 0x54, 0xbf,
0xfe, 0x8b, 0x4d, 0xc7, 0x72, 0xc1, 0x4d, 0x98, 0xb6, 0x96, 0xa1, 0xbb, 0xfb,
0x5c, 0xa3, 0x2c, 0x43, 0x6c, 0xc6, 0x1c, 0x16, 0x56, 0x37, 0x90, 0x30, 0x6c,
0x79, 0xea, 0xca, 0x77, 0x05, 0x66, 0x8b, 0x47, 0xdf, 0xfe, 0x5b, 0xb6,
],
CompressedRistretto([
0x30, 0x66, 0xf8, 0x2a, 0x1a, 0x74, 0x7d, 0x45, 0x12, 0x0d, 0x17, 0x40, 0xf1,
0x43, 0x58, 0x53, 0x1a, 0x8f, 0x04, 0xbb, 0xff, 0xe6, 0xa8, 0x19, 0xf8, 0x6d,
0xfe, 0x50, 0xf4, 0x4a, 0x0a, 0x46,
]),
),
(
[
0xf1, 0x16, 0xb3, 0x4b, 0x8f, 0x17, 0xce, 0xb5, 0x6e, 0x87, 0x32, 0xa6, 0x0d,
0x91, 0x3d, 0xd1, 0x0c, 0xce, 0x47, 0xa6, 0xd5, 0x3b, 0xee, 0x92, 0x04, 0xbe,
0x8b, 0x44, 0xf6, 0x67, 0x8b, 0x27, 0x01, 0x02, 0xa5, 0x69, 0x02, 0xe2, 0x48,
0x8c, 0x46, 0x12, 0x0e, 0x92, 0x76, 0xcf, 0xe5, 0x46, 0x38, 0x28, 0x6b, 0x9e,
0x4b, 0x3c, 0xdb, 0x47, 0x0b, 0x54, 0x2d, 0x46, 0xc2, 0x06, 0x8d, 0x38,
],
CompressedRistretto([
0xf2, 0x6e, 0x5b, 0x6f, 0x7d, 0x36, 0x2d, 0x2d, 0x2a, 0x94, 0xc5, 0xd0, 0xe7,
0x60, 0x2c, 0xb4, 0x77, 0x3c, 0x95, 0xa2, 0xe5, 0xc3, 0x1a, 0x64, 0xf1, 0x33,
0x18, 0x9f, 0xa7, 0x6e, 0xd6, 0x1b,
]),
),
(
[
0x84, 0x22, 0xe1, 0xbb, 0xda, 0xab, 0x52, 0x93, 0x8b, 0x81, 0xfd, 0x60, 0x2e,
0xff, 0xb6, 0xf8, 0x91, 0x10, 0xe1, 0xe5, 0x72, 0x08, 0xad, 0x12, 0xd9, 0xad,
0x76, 0x7e, 0x2e, 0x25, 0x51, 0x0c, 0x27, 0x14, 0x07, 0x75, 0xf9, 0x33, 0x70,
0x88, 0xb9, 0x82, 0xd8, 0x3d, 0x7f, 0xcf, 0x0b, 0x2f, 0xa1, 0xed, 0xff, 0xe5,
0x19, 0x52, 0xcb, 0xe7, 0x36, 0x5e, 0x95, 0xc8, 0x6e, 0xaf, 0x32, 0x5c,
],
CompressedRistretto([
0x00, 0x6c, 0xcd, 0x2a, 0x9e, 0x68, 0x67, 0xe6, 0xa2, 0xc5, 0xce, 0xa8, 0x3d,
0x33, 0x02, 0xcc, 0x9d, 0xe1, 0x28, 0xdd, 0x2a, 0x9a, 0x57, 0xdd, 0x8e, 0xe7,
0xb9, 0xd7, 0xff, 0xe0, 0x28, 0x26,
]),
),
(
[
0xac, 0x22, 0x41, 0x51, 0x29, 0xb6, 0x14, 0x27, 0xbf, 0x46, 0x4e, 0x17, 0xba,
0xee, 0x8d, 0xb6, 0x59, 0x40, 0xc2, 0x33, 0xb9, 0x8a, 0xfc, 0xe8, 0xd1, 0x7c,
0x57, 0xbe, 0xeb, 0x78, 0x76, 0xc2, 0x15, 0x0d, 0x15, 0xaf, 0x1c, 0xb1, 0xfb,
0x82, 0x4b, 0xbd, 0x14, 0x95, 0x5f, 0x2b, 0x57, 0xd0, 0x8d, 0x38, 0x8a, 0xab,
0x43, 0x1a, 0x39, 0x1c, 0xfc, 0x33, 0xd5, 0xba, 0xfb, 0x5d, 0xbb, 0xaf,
],
CompressedRistretto([
0xf8, 0xf0, 0xc8, 0x7c, 0xf2, 0x37, 0x95, 0x3c, 0x58, 0x90, 0xae, 0xc3, 0x99,
0x81, 0x69, 0x00, 0x5d, 0xae, 0x3e, 0xca, 0x1f, 0xbb, 0x04, 0x54, 0x8c, 0x63,
0x59, 0x53, 0xc8, 0x17, 0xf9, 0x2a,
]),
),
(
[
0x16, 0x5d, 0x69, 0x7a, 0x1e, 0xf3, 0xd5, 0xcf, 0x3c, 0x38, 0x56, 0x5b, 0xee,
0xfc, 0xf8, 0x8c, 0x0f, 0x28, 0x2b, 0x8e, 0x7d, 0xbd, 0x28, 0x54, 0x4c, 0x48,
0x34, 0x32, 0xf1, 0xce, 0xc7, 0x67, 0x5d, 0xeb, 0xea, 0x8e, 0xbb, 0x4e, 0x5f,
0xe7, 0xd6, 0xf6, 0xe5, 0xdb, 0x15, 0xf1, 0x55, 0x87, 0xac, 0x4d, 0x4d, 0x4a,
0x1d, 0xe7, 0x19, 0x1e, 0x0c, 0x1c, 0xa6, 0x66, 0x4a, 0xbc, 0xc4, 0x13,
],
CompressedRistretto([
0xae, 0x81, 0xe7, 0xde, 0xdf, 0x20, 0xa4, 0x97, 0xe1, 0x0c, 0x30, 0x4a, 0x76,
0x5c, 0x17, 0x67, 0xa4, 0x2d, 0x6e, 0x06, 0x02, 0x97, 0x58, 0xd2, 0xd7, 0xe8,
0xef, 0x7c, 0xc4, 0xc4, 0x11, 0x79,
]),
),
(
[
0xa8, 0x36, 0xe6, 0xc9, 0xa9, 0xca, 0x9f, 0x1e, 0x8d, 0x48, 0x62, 0x73, 0xad,
0x56, 0xa7, 0x8c, 0x70, 0xcf, 0x18, 0xf0, 0xce, 0x10, 0xab, 0xb1, 0xc7, 0x17,
0x2d, 0xdd, 0x60, 0x5d, 0x7f, 0xd2, 0x97, 0x98, 0x54, 0xf4, 0x7a, 0xe1, 0xcc,
0xf2, 0x04, 0xa3, 0x31, 0x02, 0x09, 0x5b, 0x42, 0x00, 0xe5, 0xbe, 0xfc, 0x04,
0x65, 0xac, 0xcc, 0x26, 0x31, 0x75, 0x48, 0x5f, 0x0e, 0x17, 0xea, 0x5c,
],
CompressedRistretto([
0xe2, 0x70, 0x56, 0x52, 0xff, 0x9f, 0x5e, 0x44, 0xd3, 0xe8, 0x41, 0xbf, 0x1c,
0x25, 0x1c, 0xf7, 0xdd, 0xdb, 0x77, 0xd1, 0x40, 0x87, 0x0d, 0x1a, 0xb2, 0xed,
0x64, 0xf1, 0xa9, 0xce, 0x86, 0x28,
]),
),
(
[
0x2c, 0xdc, 0x11, 0xea, 0xeb, 0x95, 0xda, 0xf0, 0x11, 0x89, 0x41, 0x7c, 0xdd,
0xdb, 0xf9, 0x59, 0x52, 0x99, 0x3a, 0xa9, 0xcb, 0x9c, 0x64, 0x0e, 0xb5, 0x05,
0x8d, 0x09, 0x70, 0x2c, 0x74, 0x62, 0x2c, 0x99, 0x65, 0xa6, 0x97, 0xa3, 0xb3,
0x45, 0xec, 0x24, 0xee, 0x56, 0x33, 0x5b, 0x55, 0x6e, 0x67, 0x7b, 0x30, 0xe6,
0xf9, 0x0a, 0xc7, 0x7d, 0x78, 0x10, 0x64, 0xf8, 0x66, 0xa3, 0xc9, 0x82,
],
CompressedRistretto([
0x80, 0xbd, 0x07, 0x26, 0x25, 0x11, 0xcd, 0xde, 0x48, 0x63, 0xf8, 0xa7, 0x43,
0x4c, 0xef, 0x69, 0x67, 0x50, 0x68, 0x1c, 0xb9, 0x51, 0x0e, 0xea, 0x55, 0x70,
0x88, 0xf7, 0x6d, 0x9e, 0x50, 0x65,
]),
),
(
[
0xed, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x12, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
],
CompressedRistretto([
0x30, 0x42, 0x82, 0x79, 0x10, 0x23, 0xb7, 0x31, 0x28, 0xd2, 0x77, 0xbd, 0xcb,
0x5c, 0x77, 0x46, 0xef, 0x2e, 0xac, 0x08, 0xdd, 0xe9, 0xf2, 0x98, 0x33, 0x79,
0xcb, 0x8e, 0x5e, 0xf0, 0x51, 0x7f,
]),
),
(
[
0xed, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
],
CompressedRistretto([
0x30, 0x42, 0x82, 0x79, 0x10, 0x23, 0xb7, 0x31, 0x28, 0xd2, 0x77, 0xbd, 0xcb,
0x5c, 0x77, 0x46, 0xef, 0x2e, 0xac, 0x08, 0xdd, 0xe9, 0xf2, 0x98, 0x33, 0x79,
0xcb, 0x8e, 0x5e, 0xf0, 0x51, 0x7f,
]),
),
(
[
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x7f,
],
CompressedRistretto([
0x30, 0x42, 0x82, 0x79, 0x10, 0x23, 0xb7, 0x31, 0x28, 0xd2, 0x77, 0xbd, 0xcb,
0x5c, 0x77, 0x46, 0xef, 0x2e, 0xac, 0x08, 0xdd, 0xe9, 0xf2, 0x98, 0x33, 0x79,
0xcb, 0x8e, 0x5e, 0xf0, 0x51, 0x7f,
]),
),
(
[
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x12, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80,
],
CompressedRistretto([
0x30, 0x42, 0x82, 0x79, 0x10, 0x23, 0xb7, 0x31, 0x28, 0xd2, 0x77, 0xbd, 0xcb,
0x5c, 0x77, 0x46, 0xef, 0x2e, 0xac, 0x08, 0xdd, 0xe9, 0xf2, 0x98, 0x33, 0x79,
0xcb, 0x8e, 0x5e, 0xf0, 0x51, 0x7f,
]),
),
];
// Check that onewaymap(input) == output for all the above vectors
for (input, output) in test_vectors {
let Q = RistrettoPoint::from_uniform_bytes(&input);
assert_eq!(&Q.compress(), output);
}
}
#[test]
fn random_roundtrip() {
let mut rng = OsRng;