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daphne: Remove 16-byte VdafVerifyKey variant #761

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Merged
cjpatton merged 1 commit into from
Jan 14, 2025
Merged

daphne: Remove 16-byte VdafVerifyKey variant #761

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44 changes: 15 additions & 29 deletions crates/daphne/src/taskprov.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -63,16 +63,14 @@ pub(crate) fn extract_prk_from_verify_key_init(
Salt::new(HKDF_SHA256, &TASKPROV_SALT).extract(verify_key_init)
}

impl VdafConfig {
fn expand_into_taskprov_verify_key(&self, prk: &Prk, task_id: &TaskId) -> VdafVerifyKey {
let mut verify_key = self.uninitialized_verify_key();
let info = [task_id.as_ref()];
// This expand(), and the associated fill() below can only fail if the length is wrong,
// and it won't be, so we unwrap().
let okm = prk.expand(&info, verify_key.clone()).unwrap();
okm.fill(verify_key.as_mut()).unwrap();
verify_key
}
fn expand_into_taskprov_verify_key(prk: &Prk, task_id: &TaskId) -> VdafVerifyKey {
let mut verify_key = VdafVerifyKey([0; 32]);
let info = [task_id.as_ref()];
// This expand(), and the associated fill() below can only fail if the length is wrong,
// and it won't be, so we unwrap().
let okm = prk.expand(&info, verify_key.clone()).unwrap();
okm.fill(verify_key.as_mut()).unwrap();
verify_key
}

/// Compute the VDAF verify key for `task_id` and the specified VDAF type using the
Expand All @@ -86,9 +84,8 @@ fn compute_vdaf_verify_key(
version: DapVersion,
verify_key_init: &[u8; 32],
task_id: &TaskId,
vdaf_config: &VdafConfig,
) -> VdafVerifyKey {
vdaf_config.expand_into_taskprov_verify_key(
expand_into_taskprov_verify_key(
&extract_prk_from_verify_key_init(version, verify_key_init),
task_id,
)
Expand Down Expand Up @@ -313,12 +310,8 @@ impl DapTaskConfigNeedsOptIn {
version,
taskprov_advertisement.vdaf_config.var,
)?;
let vdaf_verify_key = compute_vdaf_verify_key(
version,
taskprov_config.vdaf_verify_key_init,
task_id,
&vdaf,
);
let vdaf_verify_key =
compute_vdaf_verify_key(version, taskprov_config.vdaf_verify_key_init, task_id);
Ok(Self {
version,
leader_url: url_from_bytes(task_id, &taskprov_advertisement.leader_url.bytes)?,
Expand Down Expand Up @@ -465,7 +458,7 @@ mod test {
messages::{self, TaskId},
taskprov::{DapTaskConfigNeedsOptIn, OptInParam},
test_versions,
vdaf::{VdafConfig, VdafVerifyKey},
vdaf::VdafVerifyKey,
DapRequestMeta, DapVersion,
};

Expand Down Expand Up @@ -536,20 +529,13 @@ mod test {
0x0f, 0x32, 0xd7, 0xe1, 0xbc, 0x6c, 0x75, 0x10, 0x05, 0x60, 0x7b, 0x81, 0xda, 0xc3,
0xa7, 0xda, 0x76, 0x1d,
];
let vk = compute_vdaf_verify_key(
version,
&verify_key_init,
&task_id,
&VdafConfig::Prio2 { dimension: 10 },
);
let VdafVerifyKey(verify_key) =
compute_vdaf_verify_key(version, &verify_key_init, &task_id);
let expected: [u8; 32] = [
251, 209, 125, 181, 57, 15, 148, 158, 227, 45, 38, 52, 220, 73, 159, 91, 145, 40, 123,
204, 49, 124, 7, 97, 221, 4, 232, 53, 194, 171, 19, 51,
];
match &vk {
VdafVerifyKey::L32(bytes) => assert_eq!(*bytes, expected),
VdafVerifyKey::L16(..) => unreachable!(),
}
assert_eq!(verify_key, expected);
}

test_versions! { check_vdaf_key_computation }
Expand Down
8 changes: 1 addition & 7 deletions crates/daphne/src/vdaf/mastic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,17 +70,11 @@ pub(crate) fn mastic_shard(
pub(crate) fn mastic_prep_init(
input_size: usize,
weight_config: MasticWeightConfig,
verify_key: &VdafVerifyKey,
_verify_key: &VdafVerifyKey,
agg_param: &DapAggregationParam,
public_share_bytes: &[u8],
input_share_bytes: &[u8],
) -> Result<(VdafPrepState, VdafPrepShare), VdafError> {
let VdafVerifyKey::L16(_verify_key) = verify_key else {
return Err(VdafError::Dap(fatal_error!(
err = "mastic: unexpected verify key type"
)));
};

match (weight_config, agg_param) {
(MasticWeightConfig::Count, DapAggregationParam::Mastic(agg_param)) => {
// Simulate Mastic, insecurely. The public share encodes the plaintext input; the input
Expand Down
53 changes: 8 additions & 45 deletions crates/daphne/src/vdaf/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -388,38 +388,23 @@ impl std::fmt::Display for Prio3Config {
any(test, feature = "test-utils"),
derive(deepsize::DeepSizeOf, PartialEq, Debug)
)]
pub enum VdafVerifyKey {
/// Prio3 with the standard XOF.
L16(#[serde(with = "hex")] [u8; 16]),

/// Prio2 and Prio3 with `XofHmacSha256Aes128`.
L32(#[serde(with = "hex")] [u8; 32]),
}
pub struct VdafVerifyKey(#[serde(with = "hex")] pub(crate) [u8; 32]);

impl KeyType for VdafVerifyKey {
fn len(&self) -> usize {
match self {
Self::L16(bytes) => bytes.len(),
Self::L32(bytes) => bytes.len(),
}
32
}
}

impl AsRef<[u8]> for VdafVerifyKey {
fn as_ref(&self) -> &[u8] {
match self {
Self::L16(bytes) => &bytes[..],
Self::L32(bytes) => &bytes[..],
}
&self.0
}
}

impl AsMut<[u8]> for VdafVerifyKey {
fn as_mut(&mut self) -> &mut [u8] {
match self {
Self::L16(bytes) => &mut bytes[..],
Self::L32(bytes) => &mut bytes[..],
}
&mut self.0
}
}

Expand Down Expand Up @@ -646,39 +631,17 @@ impl Encode for VdafAggregateShare {
}

impl VdafConfig {
pub(crate) fn uninitialized_verify_key(&self) -> VdafVerifyKey {
match self {
Self::Prio2 { .. } | Self::Prio3(..) => VdafVerifyKey::L32([0; 32]),
#[cfg(feature = "experimental")]
Self::Mastic { .. } => VdafVerifyKey::L16([0; 16]),
Self::Pine(..) => VdafVerifyKey::L32([0; 32]),
}
}

/// Parse a verification key from raw bytes.
pub fn get_decoded_verify_key(&self, bytes: &[u8]) -> Result<VdafVerifyKey, CodecError> {
match self {
Self::Prio2 { .. } | Self::Prio3(..) => Ok(VdafVerifyKey::L32(
<[u8; 32]>::try_from(bytes)
.map_err(|e| CodecErrorDraft09::Other(Box::new(e)))
.map_err(upgrade_codec_error)?,
)),
#[cfg(feature = "experimental")]
Self::Mastic { .. } => Ok(VdafVerifyKey::L16(
<[u8; 16]>::try_from(bytes).map_err(|e| CodecError::Other(Box::new(e)))?,
)),
Self::Pine(..) => Ok(VdafVerifyKey::L32(
<[u8; 32]>::try_from(bytes)
.map_err(|e| CodecErrorDraft09::Other(Box::new(e)))
.map_err(upgrade_codec_error)?,
)),
}
Ok(VdafVerifyKey(
<[u8; 32]>::try_from(bytes).map_err(|_| CodecError::UnexpectedValue)?,
))
}

/// Generate the Aggregators' shared verification parameters.
pub fn gen_verify_key(&self) -> VdafVerifyKey {
let mut rng = thread_rng();
let mut verify_key = self.uninitialized_verify_key();
let mut verify_key = VdafVerifyKey([0; 32]);
rng.fill(verify_key.as_mut());
verify_key
}
Expand Down
11 changes: 4 additions & 7 deletions crates/daphne/src/vdaf/pine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -81,14 +81,14 @@ impl PineConfig {

pub(crate) fn prep_init(
&self,
verify_key: &VdafVerifyKey,
VdafVerifyKey(verify_key): &VdafVerifyKey,
agg_id: usize,
nonce: &[u8; 16],
public_share_data: &[u8],
input_share_data: &[u8],
) -> Result<(VdafPrepState, VdafPrepShare), VdafError> {
match (self, verify_key) {
(PineConfig::Field32HmacSha256Aes128 { param }, VdafVerifyKey::L32(verify_key)) => {
match self {
PineConfig::Field32HmacSha256Aes128 { param } => {
let vdaf = pine32_hmac_sha256_aes128(param)?;
let (state, share) = prep_init(
vdaf,
Expand All @@ -103,7 +103,7 @@ impl PineConfig {
VdafPrepShare::Pine32HmacSha256Aes128(share),
))
}
(PineConfig::Field64HmacSha256Aes128 { param }, VdafVerifyKey::L32(verify_key)) => {
PineConfig::Field64HmacSha256Aes128 { param } => {
let vdaf = pine64_hmac_sha256_aes128(param)?;
let (state, share) = prep_init(
vdaf,
Expand All @@ -118,9 +118,6 @@ impl PineConfig {
VdafPrepShare::Pine64HmacSha256Aes128(share),
))
}
_ => Err(VdafError::Dap(fatal_error!(
err = "unhandled config and verify key combination",
))),
}
}

Expand Down
8 changes: 1 addition & 7 deletions crates/daphne/src/vdaf/prio2.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,18 +55,12 @@ pub(crate) fn prio2_shard(
/// Consume an input share and return the corresponding prep state and share.
pub(crate) fn prio2_prep_init(
dimension: usize,
verify_key: &VdafVerifyKey,
VdafVerifyKey(verify_key): &VdafVerifyKey,
agg_id: usize,
nonce: &[u8; 16],
public_share_data: &[u8],
input_share_data: &[u8],
) -> Result<(VdafPrepState, VdafPrepShare), VdafError> {
let VdafVerifyKey::L32(verify_key) = verify_key else {
return Err(VdafError::Dap(fatal_error!(
err = "unhandled verify key type"
)));
};

let vdaf = Prio2::new(dimension).map_err(|e| {
VdafError::Dap(fatal_error!(err = ?e, "failed to create prio2 from {dimension}"))
})?;
Expand Down
15 changes: 4 additions & 11 deletions crates/daphne/src/vdaf/prio3.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -111,15 +111,15 @@ impl Prio3Config {
pub(crate) fn prep_init(
&self,
version: DapVersion,
verify_key: &VdafVerifyKey,
VdafVerifyKey(verify_key): &VdafVerifyKey,
task_id: TaskId,
agg_id: usize,
nonce: &[u8; 16],
public_share_data: &[u8],
input_share_data: &[u8],
) -> Result<(VdafPrepState, VdafPrepShare), VdafError> {
return match (version, self, verify_key) {
(DapVersion::Latest, Prio3Config::Count, VdafVerifyKey::L32(verify_key)) => {
return match (version, self) {
(DapVersion::Latest, Prio3Config::Count) => {
let vdaf = Prio3::new_count(2).map_err(|e| {
VdafError::Dap(fatal_error!(err = ?e, "initializing {self:?} failed"))
})?;
Expand All @@ -137,11 +137,7 @@ impl Prio3Config {
VdafPrepShare::Prio3Field64(share),
))
}
(
DapVersion::Latest,
Prio3Config::Sum { max_measurement },
VdafVerifyKey::L32(verify_key),
) => {
(DapVersion::Latest, Prio3Config::Sum { max_measurement }) => {
let vdaf = Prio3::new_sum(2, *max_measurement).map_err(|e| {
VdafError::Dap(fatal_error!(err = ?e, "initializing {self:?} failed"))
})?;
Expand All @@ -165,7 +161,6 @@ impl Prio3Config {
length,
chunk_length,
},
VdafVerifyKey::L32(verify_key),
) => {
let vdaf = Prio3::new_histogram(2, *length, *chunk_length).map_err(|e| {
VdafError::Dap(fatal_error!(err = ?e, "initializing {self:?} failed"))
Expand All @@ -191,7 +186,6 @@ impl Prio3Config {
length,
chunk_length,
},
VdafVerifyKey::L32(verify_key),
) => {
let vdaf = Prio3::new_sum_vec(2, *bits, *length, *chunk_length).map_err(|e| {
VdafError::Dap(fatal_error!(err = ?e, "initializing {self:?} failed"))
Expand All @@ -218,7 +212,6 @@ impl Prio3Config {
chunk_length,
num_proofs,
},
VdafVerifyKey::L32(verify_key),
) => {
let vdaf = draft09::new_prio3_sum_vec_field64_multiproof_hmac_sha256_aes128(
*bits,
Expand Down
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