Im trying to decrypt a text, which was encrypted with AES-256-ECB with the given key. To decrypt, Im using the same version of the openssl which was used for encryption (OpenSSL 1.1.1d 10 Sep 2019).
String to decrypt: VAWawVAWawxiyH20dI+t5NPAY9w== (inside file.txt)
Key: 461a966faef244e4808d6b2b8e928d01 (inside key.txt)
I tried those commands:
cat file.txt | base64 -d > file2.txt
openssl enc -AES-256-ECB -d -in file2.txt -out answer.txt --kfile key.txt
And im getting: bad magic number. Whats the problem?
openssl enc will normally use a password to derive a key. So it is the derived key that is used to decrypt the file. The derivation process requires a "salt", and openssl enc during encryption stores that salt at the beginning of the file along with a "magic number" to identify it. If the magic number is missing (usually because the file wasn't encrypted by openssl enc or because the password based key derivation derivation method wasn't used) then you get this error.
The -kfile option tells OpenSSL to read the password from a file and then derive the key from it. Probably want you intended was to not use password derivation at all, but to use the explicit key. In which case you need to use the -K option and supply the key on the command line using hex.
I need to encrypt a file containing one CLIENT_ID by line.
When I use
openssl enc -k jesuislacle -aes256 -base64 -e -in &_fidat/num_tie_dmp.csv -out &_fidat/decrypted_numtie.csv, I encrypt the whole file.
But what I want is to encrypt line by line. i.e.
Original I have:
ABCDEC
FGHHIJ
KLMNOP
QRSTUV
What I want :
QHXrpv3ah0qEPBECCt1//PBKiugmWYMuE+WaA4r9Rgc#
nAca0Pb6bH1cQRfkO9wReY+X6dgl44BKE/nKSFBLM+o#
UjTJsoHoLAC0GeqqImxDXX9znUtd7dGm4VODZ+T7lvM#
dcU+H+jd9RZZqweDu1nnJDWMlKjxW2Hc+Q2uAW1tQfk#
For the moment, I launch this command X times for each ID.
But I can have, more than 10000 ID to encrypt. It takes few hours to have the results. It's too much.
What's the best way.
I'm on SAS 9.3, UNIX and I have to encrypt in AES 256 not MD5 (thank's to my DPO :-) )
Thanks for your help.
Jérome
You can try this:
while read line; do
echo "$line" | openssl enc -k jesuislacle -aes256 -base64 -e;
done <infile >outfile
It reads all lines of the file one by one and encrypts it with the specified key.
I am trying to use Openssl to decrypt the following AES 128 bits CBC based64 text (not padded) contained in the input.txt
bzxCHMWF+KVMumKb6rXTJQ0803fpYyxgdtZ8/nvc0Fc=
the first 16bytes are the IV. the encryption key is h4ckth1sk3yp4d16
I tried using the command:
openssl enc -aes-128-cbc -d -base64 -K 6834636b746831736b33797034643136 -iv 627a7843484d57462b4b564d756d4b62 -in input.txt -out result.txt
in the input.txt, I remove the first 16 bytes of the encrypted text when running the above command.
but I kept getting the error:
bad decrypt 3073874120:error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length:evp_enc.c:532:
can anyone tell what's wrong here? thanks!
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.