Bcrypt password hashing

Description

Bcrypt is used for secure password hashing. The main difference with regular digest algorithms such as MD5 or SHA256 is that the bcrypt algorithm is specifically designed to be CPU intensive in order to protect against brute force attacks. The exact complexity of the algorithm is configurable via the log_rounds parameter. The interface is fully compatible with the Python one.

Usage

1
2
3
4
5
gensalt(log_rounds = 12)

hashpw(password, salt = gensalt())

checkpw(password, hash)

Arguments

log_rounds

integer between 4 and 31 that defines the complexity of the hashing, increasing the cost as 2^log_rounds.

password

the message (password) to encrypt

salt

a salt generated with gensalt.

hash

the previously generated bcrypt hash to verify

Details

The hashpw function calculates a hash from a password using a random salt. Validating the hash is done by reshashing the password using the hash as a salt. The checkpw function is a simple wrapper that does exactly this.

gensalt generates a random text salt for use with hashpw. The first few characters in the salt string hold the bcrypt version number and value for log_rounds. The remainder stores 16 bytes of base64 encoded randomness for seeding the hashing algorithm.

Examples

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
# Secret message as a string
passwd <- "supersecret"

# Create the hash
hash <- hashpw(passwd)
hash

# To validate the hash
identical(hash, hashpw(passwd, hash))

# Or use the wrapper
checkpw(passwd, hash)

# Use varying complexity:
hash11 <- hashpw(passwd, gensalt(11))
hash12 <- hashpw(passwd, gensalt(12))
hash13 <- hashpw(passwd, gensalt(13))

# Takes longer to verify (or crack)
system.time(checkpw(passwd, hash11))
system.time(checkpw(passwd, hash12))
system.time(checkpw(passwd, hash13))

Want to suggest features or report bugs for rdrr.io? Use the GitHub issue tracker.