[WIP] Bound RsaPublicKey::new on 4096-bits; add ::new_large
#171
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This commit fixes #166 by enforcing a 4096-bit upper limit by default, which prevents potential DoS by using maliciously large RSA keys. The PKCS#1/PKCS#8 parsers use this API, limiting the size of keys parsed from these formats to 4096-bits. An `RsaPrivateKey::new_large` constructor has been added which enforces the 16384-bit limit added in #170. This can be used for unusual applications that need to support larger keys. `RsaPrivateKey::from_components` uses the `::new_large` constructor, so private keys follow the 16384-bit limit only. The `RsaPrivateKey::MAX_SIZE` and `RsaPrivateKey::MAX_SIZE_LARGE` inherent constants specify the maximum allowed sizes.
tarcieri
commented
Jul 30, 2022
Comment on lines
+229
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| pub const MIN_PUB_EXPONENT: u64 = 2; | ||
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| /// Maximum value of the public exponent `e`. | ||
| pub const MAX_PUB_EXPONENT: u64 = (1 << 33) - 1; |
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Feels a bit weird to make these pub as u64. I think it'd be nice to have access to them, but there is a mismatch between u64 here and BigUint when passed as a parameter.
Perhaps we should make e: u64 as well? (that can be done in a separate PR)
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Having two APIs that are essentially the same thing feels a little clunky. Why not add a Something like: pub struct Limits {
/// The maximum key size in bytes
pub max_key_size: usize,
}
impl Default for Limits {
fn default() -> Self {
Limits { max_key_size: 4096 }
}
}
pub fn new(n: BigUint, e: BigUint, limits: Limits) -> Result<Self> {
// ...
} |
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That needlessly complicates the common-case API. However, we could have two methods, where one is composed in terms of the other, e.g. |
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Closing in favor of #176 |
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NOTE: depends on #170
This commit fixes #166 by enforcing a 4096-bit upper limit by default, which prevents potential DoS by using maliciously large RSA keys.
The PKCS#1/PKCS#8 parsers use this API, limiting the size of keys parsed from these formats to 4096-bits.
An
RsaPrivateKey::new_largeconstructor has been added which enforces the 16384-bit limit added in #170. This can be used for unusual applications that need to support larger keys.RsaPrivateKey::from_componentsuses the::new_largeconstructor, so private keys follow the 16384-bit limit only.The
RsaPrivateKey::MAX_SIZEandRsaPrivateKey::MAX_SIZE_LARGEinherent constants specify the maximum allowed sizes.