Function verify_signatures 

pub fn verify_signatures<'a, D, M, I>(
    role: &MetadataPath,
    raw_metadata: &RawSignedMetadata<D, M>,
    threshold: u32,
    authorized_keys: I,
) -> Result<Verified<M>, Error>
where
    D: Pouf,
    M: Metadata,
    I: IntoIterator<Item = &'a PublicKey>,

Verify this metadata.

let key_1: &[u8] = include_bytes!("../tests/ed25519/ed25519-1.pk8.der");
let key_1 = Ed25519PrivateKey::from_pkcs8(&key_1).unwrap();

let key_2: &[u8] = include_bytes!("../tests/ed25519/ed25519-2.pk8.der");
let key_2 = Ed25519PrivateKey::from_pkcs8(&key_2).unwrap();

let raw_snapshot = SnapshotMetadataBuilder::new()
    .signed::<Pouf1>(&key_1)
    .unwrap()
    .to_raw()
    .unwrap();

assert!(verify_signatures(
    &MetadataPath::snapshot(),
    &raw_snapshot,
    1,
    vec![key_1.public()],
).is_ok());

// fail with increased threshold
assert!(verify_signatures(
    &MetadataPath::snapshot(),
    &raw_snapshot,
    2,
    vec![key_1.public()],
).is_err());

// fail when the keys aren't authorized
assert!(verify_signatures(
    &MetadataPath::snapshot(),
    &raw_snapshot,
    1,
    vec![key_2.public()],
).is_err());

// fail when the keys don't exist
assert!(verify_signatures(
    &MetadataPath::snapshot(),
    &raw_snapshot,
    1,
    &[],
).is_err());