I'm trying to use OpenSSL for authenticated encryption. Specifically, I'm trying to use AES-256-GCM (or CCM).
However, when I run openssl list-cipher-commands, I don't see it. The only AES ciphers shown are these:
aes-128-cbc
aes-128-ecb
aes-192-cbc
aes-192-ecb
aes-256-cbc
aes-256-ecb
I'm on openssl 1.0.1e, so it should be supported.
OpenSSL supports aes-256-gcm as an algorithm, but it does not support aes-256-gcm as a command tool. The difference is that you can enter openssl aes-256-cbc in the command line to encrypt something. On the other hand, there are no such openssl aes-256-gcm command line tool.
You can use the EVP interface to call aes-256-gcm algorithm, as this answer shows.
By the way, you may try to use openssl enc aes-256-gcm in the command line. That does not work either, because no additional authenticated data will be handled by the enc command. See more information here.
Related
I am using 1.0.2p to encrypt the file using the following command.
#openssl aes-128-cbc -e -k 'abcdefghijklmnop' -in my.txt -out myencrypt.txt
My decryption is based out of Crypto.Cipher python module.
Here is my code. However, I am unable to decrypt the text successfully.
I am unsure on what am I missing here?
from Crypto.Cipher import AES
def decrypt(ciphertext, key):
iv = ciphertext[:AES.block_size]
cipher = AES.new(key, AES.MODE_CBC, iv)
plaintext = cipher.decrypt(ciphertext[AES.block_size:])
return plaintext.rstrip(b"\0")
def decrypt_file(file_name, key):
with open(file_name, 'rb') as encrypt_file:
ciphertext = encrypt_file.read()
dec = decrypt(ciphertext, key)
with open("plain.txt", "wb") as plain_file:
plain_file.write(dec)
if __name__ == "__main__":
decrypt_file('myencrypt.txt', 'abcdefghijklmnop')
Your issue could be that OpenSSL 1.0.2 still uses MD5 as its hashing algorithm instead of SHA. I am not super familiar with this Python library, but from the docs it looks like the default hashing algorithm is SHA1.
From the parameters section of new():
hashAlgo (hash object) – The hash function to use. This can be a module under Crypto.Hash or an existing hash object created from any of such modules. If not specified, Crypto.Hash.SHA1 is used.
So what I believe is happening is that your encryption line (using OpenSSL 1.0.2) uses MD5 when encrypting, but the Python library is defaulting to SHA1. So you would either need to update your OpenSSL version and/or specify the hashing algorithm in your Python code when calling new().
I believe OpenSSL was updated in 1.1.0 to use a SHA algorithm for hashing. I have actually ran into this problem when trying to decrypt an archive from an older server, using OpenSSL for both encryption and decryption but the versions won't match. If you have any issues decrypting an archive from an older version of OpenSSL, you may have to specify the older hashing algorithm with -md md5, like:
openssl enc -aes256 -d -in your/input/file.encrypt -out your/output/file -md md5
I would like to decrypt a text using a 32 characters key and a salt from command line in my MacOS. I have encrypted it in Windows using a program. But, whenever I try to decrypt it from command line I couldn't and get an error.
echo -n PuYNZO+SLqFo6g97gxKr2uAPRUph/sZgaJ3T5YIBPIc= | openssl enc -d -a -aes-256-cbc -K TheTestKeyUsedIs32CharactersLong -S 53616c7455736564 -iv 0 -p
hex string is too short, padding with zero bytes to length
hex string is too short, padding with zero bytes to length
non-hex digit
invalid hex key value
When I try to encrypt
100836
in MacOS it gives me completely different string.
U2FsdGVkX19TYWx0VXNlZA4AWDWo5nzi8p5pYyAeUMg=
using following command:
openssl enc -aes-256-cbc -a -S 53616c7455736564 -iter 5 -k TheTestKeyUsedIs32CharactersLong -in input.txt -out openssl_output.txt
From the application I am using in Windows
100836
is converting into
PuYNZO+SLqFo6g97gxKr2uAPRUph/sZgaJ3T5YIBPIc=
My salt text is SaltUsed
My 32 bit character key is TheTestKeyUsedIs32CharactersLong
Input is PuYNZO+SLqFo6g97gxKr2uAPRUph/sZgaJ3T5YIBPIc=
Should be decrypted in 100836
But, result is completely unexpected.
I have also tried a java program to decrypt it but there I was getting other strings so thought to correct it with command line first and then will jump into the code.
I also tried the key in hex digits but still the response was incorrect and was not as expected.
#Wasif and I spent some time debugging in chat and in the end believe it's most likely a compatbility issue between OpenSSL 1.1.1.d on Windows and OpenSSL 1.1.1.b on macOS.
We went through a number of tests and permutations, using (Key, IV) tuples in hex, using passwords, with and without salts, and ultimately our testing came down to a simple check.
Using openssl enc -a -aes-256-cbc -pass pass:MYPASSWORD -p -in input.txt on Windows we got:
salt=E70092FEBA619144
key=29631452F8C259DFE6FD8E9372EC4B20392395F36B7A0B11769CEBEA987E90A0
iv =93BF2E94462A43B23EF585C0F4B3F1A8
U2FsdGVkX1/nAJL+umGRRGi3ybIPFXf7qrgov7SyXnI=
Using openssl aes-256-cbc -d -a -pass pass:MYPASSWORD -in cipherText.txt (which contains 'U2FsdGVkX1/nAJL+umGRRGi3ybIPFXf7qrgov7SyXnI=' on the Mac we got:
4593573484:error:06FFF064:digital envelope routines:CRYPTO_internal:bad decrypt
Despite this simple test failing, the Mac and Windows boxes successfully encrypted and decrypted locally.
Weird, but this looks like version incompatibility.
Try specifying the digest alorithm:
Default digest has changed between different versions.
See
How to resolve the "EVP_DecryptFInal_ex: bad decrypt" during file decryption
It is a large file to encrypt. I am at the encrypting part. The error is showing:
"Error reading password from Bios"
"Error getting password."
Please let me know what to do. Thanks in advance.
I kind of want to remove cbc mode because it is slow. I read it in an article. Also, the directions say to make it faster since it is needed for three users.
I think this is the problem by using 192 instead of 4096 or higher but I need to lower it to make it go faster speed from the question.
openssl genrsa -aes256 -out pubPrivate.key 192
openssl enc -aes-256-cbc -in BigFile.txt -out cipher.bin -pass File: pubPrivate.key
Also, I read somewhere that there are numbers 0000 in front of the code somewhere causing the error if that matters?
It's unclear what you are trying to do. Encrypt a large file, sure. But how? Symmetric with AES, or asymmetric with RSA?
Your first command, openssl genrsa creates a RSA public/private keypair with length 192, which as Ken White notes is a bad idea, not only is it not a power of 2, but also an incredibly short key length; to give you an estimate of how bad this is, 512 bit RSA keys were broken twenty years ago. In fact, my openssl, version 1.1.1b plainly refuses to even create such a keypair:
$ openssl genrsa -aes256 -out foo.key 192
Generating RSA private key, 192 bit long modulus (2 primes)
25769803792:error:04081078:rsa routines:rsa_builtin_keygen:key size too small:crypto/rsa/rsa_gen.c:78:
Your second command then does something completely different. It tries to encrypt Bigfile.txt using AES256 in CBC mode, which is ok, but you don't give the command a 256bit AES key. Instead, you tell it to look in the RSA key file for a passphrase, which is certainly not what you want. Openssl does not accept this either:
$ openssl enc -aes-256-cbc -in BigFile.txt -out cipher.bin -pass File: pubPrivate.key
Extra arguments given.
enc: Use -help for summary.
So let's assume what you want is to encrypt BigFile.txt symmetrically, with AES256 in CBC mode using a key derived from a password. You would then distribute this password to you three recipients. How fast is this? On my laptop, with a 1GB BigFile.txt:
$ time openssl enc -aes-256-cbc -in BigFile.txt -out cipher.bin -pass pass:start123
*** WARNING : deprecated key derivation used.
Using -iter or -pbkdf2 would be better.
real 0m3,099s
user 0m1,562s
sys 0m0,968s
So, openssl encrypts around 330MB/sec, and it also tells us that the key derivation is unsafe, and we should use PBKDF2 instead. Let's do this:
$ time openssl enc -aes-256-cbc -in BigFile.txt -out cipher.bin -pbkdf2 -pass pass:start123
real 0m3,202s
user 0m1,656s
sys 0m1,077s
I forgot the password to my bitcoin backup and would like to brute-force decrypt it.
I have been given this information;
"The manual backup files are encrypted using your chosen backup password. You can use OpenSSL to decrypt:
openssl enc -d -aes-256-cbc -a -in <filename>"
Unfortunately, I don't have much experience doing this and all I can do it get it in terminal asking for the password. Can anybody give me instructions on how to brute-force decrypt a file using OpenSSL?
n.b. The password was quite simple, using only letters and perhaps one number.
... all I can do it get it in terminal asking for the password.
You need to add -passin pass:XXX options, where XXX is the password you want to try.
There's more options for -passin, see PASS PHRASE ARGUMENTS for openssl(1) command.
You will also need to understand the -k and -K options to openssl enc.
Can anybody give me instructions on how to brute-force decrypt a file using OpenSSL?
Run something like this in a loop:
# Build your list of candidates
PASSWORDS=...
for PASSWORD in $PASSWORDS; do
openssl enc -d -aes-256-cbc -a -in <filename> -passin pass:$PASSWORD
RET=$?
if [ $RET -eq 0 ]; then
echo "Candidate password: $PASSWORD"
fi
done
openssl enc returns 0 on success, non-zero otherwise. Note: you will get false positives because AES/CBC can only determine if "decryption works" based on getting the padding right. If the file decrypts but is not recovered, then remove that candidate password.
Authenticated encryption would fix the ambiguity, but you would have needed to encrypt with AES/CCM, AES/GCM, AES/EAX etc.
If you want to try on your own there is now a bruteforcing tool that will do it very efficiently, called bruteforce-salted-openssl. Note that the digest used back in the days by openssl was md5 (rather than sha256 today), so you would have to specify the digest (-m md5)
I want to encrypt and decrypt one file using one password.
How can I use OpenSSL to do that?
Security Warning: AES-256-CBC does not provide authenticated encryption and is vulnerable to padding oracle attacks. You should use something like age instead.
Encrypt:
openssl aes-256-cbc -a -salt -pbkdf2 -in secrets.txt -out secrets.txt.enc
Decrypt:
openssl aes-256-cbc -d -a -pbkdf2 -in secrets.txt.enc -out secrets.txt.new
More details on the various flags
Better Alternative: GPG
Though you have specifically asked about OpenSSL you might want to consider using GPG instead for the purpose of encryption based on this article OpenSSL vs GPG for encrypting off-site backups?
To use GPG to do the same you would use the following commands:
To Encrypt:
gpg --output encrypted.data --symmetric --cipher-algo AES256 un_encrypted.data
To Decrypt:
gpg --output un_encrypted.data --decrypt encrypted.data
Note: You will be prompted for a password when encrypting or decrypt. And use --no-symkey-cache flag for no cache.
RE: OpenSSL - Short Answer
You likely want to use gpg instead of openssl so see "Additional Notes" at the end of this answer. But to answer the question using openssl:
To Encrypt:
openssl enc -aes-256-cbc -in un_encrypted.data -out encrypted.data
To Decrypt:
openssl enc -d -aes-256-cbc -in encrypted.data -out un_encrypted.data
Note: You will be prompted for a password when encrypting or decrypt.
RE: OpenSSL - Long Answer
Your best source of information for openssl enc would probably be: https://www.openssl.org/docs/man1.1.1/man1/enc.html
Command line:
openssl enc takes the following form:
openssl enc -ciphername [-in filename] [-out filename] [-pass arg]
[-e] [-d] [-a/-base64] [-A] [-k password] [-kfile filename]
[-K key] [-iv IV] [-S salt] [-salt] [-nosalt] [-z] [-md] [-p] [-P]
[-bufsize number] [-nopad] [-debug] [-none] [-engine id]
Explanation of most useful parameters with regards to your question:
-e
Encrypt the input data: this is the default.
-d
Decrypt the input data.
-k <password>
Only use this if you want to pass the password as an argument.
Usually you can leave this out and you will be prompted for a
password. The password is used to derive the actual key which
is used to encrypt your data. Using this parameter is typically
not considered secure because your password appears in
plain-text on the command line and will likely be recorded in
bash history.
-kfile <filename>
Read the password from the first line of <filename> instead of
from the command line as above.
-a
base64 process the data. This means that if encryption is taking
place the data is base64 encoded after encryption. If decryption
is set then the input data is base64 decoded before being
decrypted.
You likely DON'T need to use this. This will likely increase the
file size for non-text data. Only use this if you need to send
data in the form of text format via email etc.
-salt
To use a salt (randomly generated) when encrypting. You always
want to use a salt while encrypting. This parameter is actually
redundant because a salt is used whether you use this or not
which is why it was not used in the "Short Answer" above!
-K key
The actual key to use: this must be represented as a string
comprised only of hex digits. If only the key is specified, the
IV must additionally be specified using the -iv option. When
both a key and a password are specified, the key given with the
-K option will be used and the IV generated from the password
will be taken. It probably does not make much sense to specify
both key and password.
-iv IV
The actual IV to use: this must be represented as a string
comprised only of hex digits. When only the key is specified
using the -K option, the IV must explicitly be defined. When a
password is being specified using one of the other options, the
IV is generated from this password.
-md digest
Use the specified digest to create the key from the passphrase.
The default algorithm as of this writing is sha-256. But this
has changed over time. It was md5 in the past. So you might want
to specify this parameter every time to alleviate problems when
moving your encrypted data from one system to another or when
updating openssl to a newer version.
Encrypt:
openssl enc -in infile.txt -out encrypted.dat -e -aes256 -k symmetrickey
Decrypt:
openssl enc -in encrypted.dat -out outfile.txt -d -aes256 -k symmetrickey
For details, see the openssl(1) docs.
DO NOT USE OPENSSL DEFAULT KEY DERIVATION.
Currently the accepted answer makes use of it and it's no longer recommended and secure.
It is very feasible for an attacker to simply brute force the key.
https://www.ietf.org/rfc/rfc2898.txt
PBKDF1 applies a hash function, which shall be MD2 [6], MD5 [19] or
SHA-1 [18], to derive keys. The length of the derived key is bounded
by the length of the hash function output, which is 16 octets for MD2
and MD5 and 20 octets for SHA-1. PBKDF1 is compatible with the key
derivation process in PKCS #5 v1.5. PBKDF1 is recommended only for compatibility with existing
applications since the keys it produces may not be large enough for
some applications.
PBKDF2 applies a pseudorandom function (see Appendix B.1 for an
example) to derive keys. The length of the derived key is essentially
unbounded. (However, the maximum effective search space for the derived key may be limited by the structure of the underlying
pseudorandom function. See Appendix B.1 for further discussion.)
PBKDF2 is recommended for new applications.
Do this:
openssl enc -aes-256-cbc -pbkdf2 -iter 20000 -in hello -out hello.enc -k meow
openssl enc -d -aes-256-cbc -pbkdf2 -iter 20000 -in hello.enc -out hello.out
Note: Iterations in decryption have to be the same as iterations in encryption.
Iterations have to be a minimum of 10000.
Here is a good answer on the number of iterations: https://security.stackexchange.com/a/3993
Also... we've got enough people here recommending GPG. Read the damn question.
As mentioned in the other answers, previous versions of openssl used a weak key derivation function to derive an AES encryption key from the password. However, openssl v1.1.1 supports a stronger key derivation function, where the key is derived from the password using pbkdf2 with a randomly generated salt, and multiple iterations of sha256 hashing (10,000 by default).
To encrypt a file:
openssl aes-256-cbc -e -salt -pbkdf2 -iter 10000 -in plaintextfilename -out encryptedfilename
To decrypt a file:
openssl aes-256-cbc -d -salt -pbkdf2 -iter 10000 -in encryptedfilename -out plaintextfilename
Note: An equivalent/compatible implementation in javascript (using the web crypto api) can be found at https://github.com/meixler/web-browser-based-file-encryption-decryption.
Update using a random generated public key.
Encypt:
openssl enc -aes-256-cbc -a -salt -in {raw data} -out {encrypted data} -pass file:{random key}
Decrypt:
openssl enc -d -aes-256-cbc -in {ciphered data} -out {raw data}
To Encrypt:
$ openssl bf < arquivo.txt > arquivo.txt.bf
To Decrypt:
$ openssl bf -d < arquivo.txt.bf > arquivo.txt
bf === Blowfish in CBC mode
There is an open source program that I find online it uses openssl to encrypt and decrypt files. It does this with a single password. The great thing about this open source script is that it deletes the original unencrypted file by shredding the file. But the dangerous thing about is once the original unencrypted file is gone you have to make sure you remember your password otherwise they be no other way to decrypt your file.
Here the link it is on github
https://github.com/EgbieAnderson1/linux_file_encryptor/blob/master/file_encrypt.py
Note that the OpenSSL CLI uses a weak non-standard algorithm to convert the passphrase to a key, and installing GPG results in various files added to your home directory and a gpg-agent background process running. If you want maximum portability and control with existing tools, you can use PHP or Python to access the lower-level APIs and directly pass in a full AES Key and IV.
Example PHP invocation via Bash:
IV='c2FtcGxlLWFlcy1pdjEyMw=='
KEY='Twsn8eh2w2HbVCF5zKArlY+Mv5ZwVyaGlk5QkeoSlmc='
INPUT=123456789023456
ENCRYPTED=$(php -r "print(openssl_encrypt('$INPUT','aes-256-ctr',base64_decode('$KEY'),OPENSSL_ZERO_PADDING,base64_decode('$IV')));")
echo '$ENCRYPTED='$ENCRYPTED
DECRYPTED=$(php -r "print(openssl_decrypt('$ENCRYPTED','aes-256-ctr',base64_decode('$KEY'),OPENSSL_ZERO_PADDING,base64_decode('$IV')));")
echo '$DECRYPTED='$DECRYPTED
This outputs:
$ENCRYPTED=nzRi252dayEsGXZOTPXW
$DECRYPTED=123456789023456
You could also use PHP's openssl_pbkdf2 function to convert a passphrase to a key securely.