rodolphe/opensmtpd-filter-sake
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Restrict key sizes to 128 or 256 bits

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This commit is contained in:
Rodolphe Bréard 2023-08-25 13:36:39 +02:00
parent 08ee559d9f
commit 4c2993b511
3 changed files with 43 additions and 16 deletions
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6
README.md
View file

@ -51,7 +51,7 @@ The `--address` option may be specified multiples times and can also be combined
In an address file, empty lines and lines starting with the `#` character are ignored.
To generate a private key, it is recommended to use the following command:
The private key's length must be either 128 or 256 bits. To generate a 128 bits key, the following command is recommended:
```
openssl rand -base64 16
@ -115,6 +115,10 @@ No, this project is based on the filter API used by OpenSMTPD.
Yes, internationalized domain names (IDN) are supported. You can specify domain names either using valid UTF-8 or Punycode ([RFC 3492](https://datatracker.ietf.org/doc/html/rfc3492)).
### How long should be my private key?
Privates keys must have a length of either 128 bits (16 bytes) or 256 bits (32 bytes). Unless you have some very specific needs, you should choose a 128 bits key.
### What about key rotation?
Rotating the key would mean that all previously generated addresses for this local part would suddenly be invalid. Therefore, the key associated with a local part must not change.

52
src/address.rs
View file

@ -119,6 +119,10 @@ impl FromStr for KeyedAddress {
.transpose()?;
let key = BASE64.decode(key_b64.as_bytes())?;
ensure!(!key.is_empty(), "{s}: key cannot be empty");
ensure!(
crate::ALLOWED_KEY_SIZES.contains(&key.len()),
"{s}: key length must be either 128 or 256 bits"
);
Ok(Self {
local_part,
domain,
@ -169,6 +173,11 @@ mod tests {
assert!(KeyedAddress::from_str("derp@").is_err());
}
#[test]
fn parse_keyed_addr_invalid_key_length() {
assert!(KeyedAddress::from_str("test:bAXk1r7mgJY=").is_err());
}
#[test]
fn parse_valid_coded_addr_with_domain() {
let addr_str = "a+test+orsxg5a@example.org";
@ -248,13 +257,19 @@ mod tests {
#[test]
fn parse_valid_keyed_addr_without_domain() {
let addr_str = "local.part:3d74YQqk";
let addr_str = "local.part:sbW22xNStWKro4nnMKmG3A==";
let addr = KeyedAddress::from_str(addr_str);
assert!(addr.is_ok(), "unable to parse {addr_str}: {addr:?}");
let addr = addr.unwrap();
assert_eq!(addr.local_part, "local.part");
assert_eq!(addr.domain, None);
assert_eq!(addr.key, vec![0xdd, 0xde, 0xf8, 0x61, 0x0a, 0xa4]);
assert_eq!(
addr.key,
vec![
0xb1, 0xb5, 0xb6, 0xdb, 0x13, 0x52, 0xb5, 0x62, 0xab, 0xa3, 0x89, 0xe7, 0x30, 0xa9,
0x86, 0xdc
]
);
}
#[test]
@ -305,77 +320,84 @@ mod tests {
#[test]
fn cmp_keyed_addr_with_domain_eq() {
let addr_1 = KeyedAddress::from_str("test@example.org:3d74YQqk").unwrap();
let addr_1 =
KeyedAddress::from_str("test@example.org:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=")
.unwrap();
let addr_2 = KeyedAddress::from_str("test@example.org:11voiefK5PgCX5F1TTcuoQ==").unwrap();
assert_eq!(addr_1, addr_2);
}
#[test]
fn cmp_keyed_addr_without_domain_eq() {
let addr_1 = KeyedAddress::from_str("test:3d74YQqk").unwrap();
let addr_1 =
KeyedAddress::from_str("test:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=").unwrap();
let addr_2 = KeyedAddress::from_str("test:11voiefK5PgCX5F1TTcuoQ==").unwrap();
assert_eq!(addr_1, addr_2);
}
#[test]
fn cmp_keyed_addr_with_domain_ne() {
let addr_1 = KeyedAddress::from_str("test@example.org:3d74YQqk").unwrap();
let addr_2 = KeyedAddress::from_str("test2@example.org:3d74YQqk").unwrap();
let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = KeyedAddress::from_str("test2@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
assert_ne!(addr_1, addr_2);
}
#[test]
fn cmp_keyed_addr_without_domain_ne() {
let addr_1 = KeyedAddress::from_str("test:3d74YQqk").unwrap();
let addr_2 = KeyedAddress::from_str("test2:3d74YQqk").unwrap();
let addr_1 =
KeyedAddress::from_str("test:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=").unwrap();
let addr_2 =
KeyedAddress::from_str("test2:gkJfLlKa2OLYItm4JD6p3hEF1kWH8LFtMK0rra8A2SQ=").unwrap();
assert_ne!(addr_1, addr_2);
}
#[test]
fn cmp_addr_types_with_domain_eq() {
let addr_1 = KeyedAddress::from_str("test@example.org:3d74YQqk").unwrap();
let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = CodedAddress::parse("test+test+orsxg5a@example.org", '+').unwrap();
assert_eq!(addr_1, addr_2);
}
#[test]
fn cmp_addr_types_without_domain_eq() {
let addr_1 = KeyedAddress::from_str("test:3d74YQqk").unwrap();
let addr_1 = KeyedAddress::from_str("test:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = CodedAddress::parse("test+test+orsxg5a", '+').unwrap();
assert_eq!(addr_1, addr_2);
}
#[test]
fn cmp_addr_types_without_sub_addr() {
let addr_1 = KeyedAddress::from_str("test@example.org:3d74YQqk").unwrap();
let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = CodedAddress::parse("test@example.org", '+').unwrap();
assert_eq!(addr_1, addr_2);
}
#[test]
fn cmp_addr_types_idna_1() {
let addr_1 = KeyedAddress::from_str("test@mél.example.org:3d74YQqk").unwrap();
let addr_1 =
KeyedAddress::from_str("test@mél.example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = CodedAddress::parse("test@xn--ml-bja.example.org", '+').unwrap();
assert_eq!(addr_1, addr_2);
}
#[test]
fn cmp_addr_types_idna_2() {
let addr_1 = KeyedAddress::from_str("test@xn--ml-bja.example.org:3d74YQqk").unwrap();
let addr_1 =
KeyedAddress::from_str("test@xn--ml-bja.example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = CodedAddress::parse("test@mél.example.org", '+').unwrap();
assert_eq!(addr_1, addr_2);
}
#[test]
fn cmp_addr_types_with_domain_ne() {
let addr_1 = KeyedAddress::from_str("test@example.org:3d74YQqk").unwrap();
let addr_1 = KeyedAddress::from_str("test@example.org:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = CodedAddress::parse("test+test+orsxg5a@example.com", '+').unwrap();
assert_ne!(addr_1, addr_2);
}
#[test]
fn cmp_addr_types_without_domain_ne() {
let addr_1 = KeyedAddress::from_str("test:3d74YQqk").unwrap();
let addr_1 = KeyedAddress::from_str("test:sbW22xNStWKro4nnMKmG3A==").unwrap();
let addr_2 = CodedAddress::parse("test2+test+orsxg5a", '+').unwrap();
assert_ne!(addr_1, addr_2);
}

1
src/main.rs
View file

@ -6,6 +6,7 @@ mod config;
mod input;
mod service;
const ALLOWED_KEY_SIZES: &[usize] = &[16, 32];
const COMMENT_CHAR: char = '#';
const DEFAULT_SEPARATOR: char = '+';
const KEY_SEPARATOR: char = ':';