Hash length |
Validity |
Meaning |
Comments |
---|---|---|---|
0 |
Valid |
Hash values returned are 0 bits long. | Hashes which return zero length hash values cannot be
used with FreeOTFE volumes. (FreeOTFE volumes use PKCS#5 PBKDF2 (HMAC), which requires that the
length of hash values returned is greater than zero.) |
Less than 0 |
Valid |
Hash values returned are of variable length (e.g. the "NULL" hash, which returns it's input as the generated hash value.) | Hashes which return variable length hash values cannot be used with FreeOTFE volumes. (FreeOTFE volumes use PKCS#5 PBKDF2 (HMAC), which requires that the length of the hash values used is fixed.) |
Greater than 0 |
Valid |
Hash values returned have a fixed, defined length (e.g. SHA-512's hash length is 512 bits) |
Must be a multiple of 8. |
Hash blocksize |
Validity |
Meaning |
Comments |
---|---|---|---|
0 |
Valid |
Hash algorithm does not process input data. | Hashes may only have a blocksize of 0
bits if the length of the hash values they output are also 0 bits long,
or if they ignore their input. Hashes which use zero length blocksizes cannot be used for FreeOTFE volumes. (FreeOTFE volumes use HMAC, which requires that the blocksize of hashes used is greater than zero.) |
Less than 0 |
Valid |
Hash algorithm processes input data in variable-length blocks. | Hashes which use variable length blocksizes cannot be used for FreeOTFE volumes. (FreeOTFE volumes use HMAC, which requires that the blocksize of hashes is a fixed size.) |
Greater than 0 |
Valid |
Hash algorithm processes input data in defined, fixed blocks (e.g. SHA-512's block size is 1024 bits) |
Must be a multiple of 8. |
Cypher keysize |
Validity |
Meaning |
Comments |
---|---|---|---|
0 |
Valid |
No key is used during encryption (e.g.
if the cypher doesn't encrypt data, just returns the plaintext as the
cyphertext; or if the cypher uses a hardcoded key) |
|
Less than 0 |
Valid |
The cypher takes variable keylengths (e.g. the "XOR" cypher) | |
Greater than 0 |
Valid |
The cypher accepts only a specific keysize (e.g. full-strength DES only accepts 64 bit keys) |
Must be a multiple of 8. |
Cypher blocksize |
Validity |
Meaning |
Comments |
---|---|---|---|
0 |
Valid |
Cypher does not process input data. (e.g. the "NULL" cypher, which just returns the supplied plaintext as cyphertext) |
If the blocksize is 0, then no IVs will be used for encrypting/decrypting. |
Less than 0 |
Valid |
Cypher processes input data in
variable-length blocks. (e.g. XOR processes data in blocks with the
same length as the key being used) |
If the blocksize isn't fixed, then then no IVs will be used for encrypting/decrypting. |
Greater than 0 |
Valid |
Cypher processes input data in defined, fixed blocks (e.g. AES has a block size is 128 bits) | Must be a multiple of 8. |