fix: Enforce byte input length for the given prime field #50
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Before this change, we were enforcing only the upper limit of the byte
input lenghts in `hash_bytes_be` and `hash_bytes_le` methods. The limit
is indicated by the amount of bytes needed to represent the modulus of
the given prime field. For the `Fr` field, the limit is 32 bytes.
At the same time, we were allowing smaller byte slices. For example,
we were allowing either a full 32-byte array with explicit padding:
```
[
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 1
]
```
Or smaller arrays with smaller amount of leading or trailing bytes
(depending on endianness):
```
[0, 0, 0, 0, 0, 0, 0, 1]
[0, 0, 0, 1]
[0, 1]
[1]
```
All these inputs produce the same hashes.
To avoid confusion, do not allow smaller inputs the modulus and make
padding mandatory.
vadorovsky
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ananas-block
approved these changes
Aug 19, 2025
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Before this change, we were enforcing only the upper limit of the byte input lenghts in
hash_bytes_beandhash_bytes_lemethods. The limit is indicated by the amount of bytes needed to represent the modulus of the given prime field. For theFrfield, the limit is 32 bytes.At the same time, we were allowing smaller byte slices. For example, we were allowing either a full 32-byte array with explicit padding:
Or smaller arrays with smaller amount of leading or trailing bytes (depending on endianness):
All these inputs produce the same hashes.
To avoid confusion, do not allow smaller inputs the modulus and make padding mandatory.