Length of AES encrypted data
I have a data that needs to be stored in a database as encrypted, the maximum length of the data before encryption is 50 chars (English or Arabic), I need to encrypt the data using AES-128 bit, and store the output in the database (base64string).
How to know the length of the data after encryption?
asp.net vb.net aes
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
add a comment |
I have a data that needs to be stored in a database as encrypted, the maximum length of the data before encryption is 50 chars (English or Arabic), I need to encrypt the data using AES-128 bit, and store the output in the database (base64string).
How to know the length of the data after encryption?
asp.net vb.net aes
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
add a comment |
I have a data that needs to be stored in a database as encrypted, the maximum length of the data before encryption is 50 chars (English or Arabic), I need to encrypt the data using AES-128 bit, and store the output in the database (base64string).
How to know the length of the data after encryption?
asp.net vb.net aes
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
I have a data that needs to be stored in a database as encrypted, the maximum length of the data before encryption is 50 chars (English or Arabic), I need to encrypt the data using AES-128 bit, and store the output in the database (base64string).
How to know the length of the data after encryption?
asp.net vb.net aes
asp.net vb.net aes
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
edited Nov 16 '18 at 21:48
Imad Abu Hayyah
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
asked Nov 16 '18 at 20:53
Imad Abu HayyahImad Abu Hayyah
947
947
add a comment |
add a comment |
1 Answer
1
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Try it with your specified algorithm, block size, IV size, and see what size output you get :-)
First it depends on the encoding of the input text. Is it UTF8? UTF16?
Lets assume UTF8 so 1 Byte per character means 50 Bytes of input data to your encryption algorithm. (100 Bytes if UTF16)
Then you will pad to the Block Size for the algorithm. AES, regardless of key size is a block of 16 Bytes. So we will be padded out to 64 Bytes (Or 112 for UTF 16)
Then we need to store the IV and header information. So that is (usually, with default settings/IV sizes) another 16Bytes so we are at 80 Bytes (Or 128 for UTF16)
Finally we are encoding to Base64. I assume you want string length, since otherwise it is wasteful to make it into a string. So Base 64 bloats the string using the following formula: Ceil(bytes/3) * 4. So for us that is Ceil(80/3) = 27 * 4 = 108 characters (Or 172 for UTF 16)
Again this is all highly dependent on your choices of how you encrypt, what the text is encoded as, etc.
I would try it with your scenario before relying on these numbers for anything useful.
answered Nov 16 '18 at 22:19
TimTim
2,1541715
Thank you for your answer, I'm using ASCII Encoding.
– Imad Abu Hayyah
Nov 16 '18 at 23:06
Lets assume UTF8 so 1 Byte? If the OP was using a US-ASCII only source. One single CodePoint outside that path and you have, possibly, 2 to 4 bytes per char.
– Jimi
Nov 16 '18 at 23:15
What about Arabic characters? Is it each char needs two bytes?
– Imad Abu Hayyah
Nov 16 '18 at 23:15
add a comment |
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1 Answer
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1 Answer
1
active
oldest
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oldest
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active
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votes
Try it with your specified algorithm, block size, IV size, and see what size output you get :-)
First it depends on the encoding of the input text. Is it UTF8? UTF16?
Lets assume UTF8 so 1 Byte per character means 50 Bytes of input data to your encryption algorithm. (100 Bytes if UTF16)
Then you will pad to the Block Size for the algorithm. AES, regardless of key size is a block of 16 Bytes. So we will be padded out to 64 Bytes (Or 112 for UTF 16)
Then we need to store the IV and header information. So that is (usually, with default settings/IV sizes) another 16Bytes so we are at 80 Bytes (Or 128 for UTF16)
Finally we are encoding to Base64. I assume you want string length, since otherwise it is wasteful to make it into a string. So Base 64 bloats the string using the following formula: Ceil(bytes/3) * 4. So for us that is Ceil(80/3) = 27 * 4 = 108 characters (Or 172 for UTF 16)
Again this is all highly dependent on your choices of how you encrypt, what the text is encoded as, etc.
I would try it with your scenario before relying on these numbers for anything useful.
answered Nov 16 '18 at 22:19
TimTim
2,1541715
Thank you for your answer, I'm using ASCII Encoding.
– Imad Abu Hayyah
Nov 16 '18 at 23:06
Lets assume UTF8 so 1 Byte? If the OP was using a US-ASCII only source. One single CodePoint outside that path and you have, possibly, 2 to 4 bytes per char.
– Jimi
Nov 16 '18 at 23:15
What about Arabic characters? Is it each char needs two bytes?
– Imad Abu Hayyah
Nov 16 '18 at 23:15
add a comment |
Try it with your specified algorithm, block size, IV size, and see what size output you get :-)
First it depends on the encoding of the input text. Is it UTF8? UTF16?
Lets assume UTF8 so 1 Byte per character means 50 Bytes of input data to your encryption algorithm. (100 Bytes if UTF16)
Then you will pad to the Block Size for the algorithm. AES, regardless of key size is a block of 16 Bytes. So we will be padded out to 64 Bytes (Or 112 for UTF 16)
Then we need to store the IV and header information. So that is (usually, with default settings/IV sizes) another 16Bytes so we are at 80 Bytes (Or 128 for UTF16)
Finally we are encoding to Base64. I assume you want string length, since otherwise it is wasteful to make it into a string. So Base 64 bloats the string using the following formula: Ceil(bytes/3) * 4. So for us that is Ceil(80/3) = 27 * 4 = 108 characters (Or 172 for UTF 16)
Again this is all highly dependent on your choices of how you encrypt, what the text is encoded as, etc.
I would try it with your scenario before relying on these numbers for anything useful.
answered Nov 16 '18 at 22:19
TimTim
2,1541715
Thank you for your answer, I'm using ASCII Encoding.
– Imad Abu Hayyah
Nov 16 '18 at 23:06
Lets assume UTF8 so 1 Byte? If the OP was using a US-ASCII only source. One single CodePoint outside that path and you have, possibly, 2 to 4 bytes per char.
– Jimi
Nov 16 '18 at 23:15
What about Arabic characters? Is it each char needs two bytes?
– Imad Abu Hayyah
Nov 16 '18 at 23:15
add a comment |
Try it with your specified algorithm, block size, IV size, and see what size output you get :-)
First it depends on the encoding of the input text. Is it UTF8? UTF16?
Lets assume UTF8 so 1 Byte per character means 50 Bytes of input data to your encryption algorithm. (100 Bytes if UTF16)
Then you will pad to the Block Size for the algorithm. AES, regardless of key size is a block of 16 Bytes. So we will be padded out to 64 Bytes (Or 112 for UTF 16)
Then we need to store the IV and header information. So that is (usually, with default settings/IV sizes) another 16Bytes so we are at 80 Bytes (Or 128 for UTF16)
Finally we are encoding to Base64. I assume you want string length, since otherwise it is wasteful to make it into a string. So Base 64 bloats the string using the following formula: Ceil(bytes/3) * 4. So for us that is Ceil(80/3) = 27 * 4 = 108 characters (Or 172 for UTF 16)
Again this is all highly dependent on your choices of how you encrypt, what the text is encoded as, etc.
I would try it with your scenario before relying on these numbers for anything useful.
answered Nov 16 '18 at 22:19
TimTim
2,1541715
Try it with your specified algorithm, block size, IV size, and see what size output you get :-)
First it depends on the encoding of the input text. Is it UTF8? UTF16?
Lets assume UTF8 so 1 Byte per character means 50 Bytes of input data to your encryption algorithm. (100 Bytes if UTF16)
Then you will pad to the Block Size for the algorithm. AES, regardless of key size is a block of 16 Bytes. So we will be padded out to 64 Bytes (Or 112 for UTF 16)
Then we need to store the IV and header information. So that is (usually, with default settings/IV sizes) another 16Bytes so we are at 80 Bytes (Or 128 for UTF16)
Finally we are encoding to Base64. I assume you want string length, since otherwise it is wasteful to make it into a string. So Base 64 bloats the string using the following formula: Ceil(bytes/3) * 4. So for us that is Ceil(80/3) = 27 * 4 = 108 characters (Or 172 for UTF 16)
Again this is all highly dependent on your choices of how you encrypt, what the text is encoded as, etc.
I would try it with your scenario before relying on these numbers for anything useful.
answered Nov 16 '18 at 22:19
TimTim
2,1541715
answered Nov 16 '18 at 22:19
TimTim
2,1541715
answered Nov 16 '18 at 22:19
TimTim
2,1541715
answered Nov 16 '18 at 22:19
TimTim
2,1541715
2,1541715
Thank you for your answer, I'm using ASCII Encoding.
– Imad Abu Hayyah
Nov 16 '18 at 23:06
Lets assume UTF8 so 1 Byte? If the OP was using a US-ASCII only source. One single CodePoint outside that path and you have, possibly, 2 to 4 bytes per char.
– Jimi
Nov 16 '18 at 23:15
What about Arabic characters? Is it each char needs two bytes?
– Imad Abu Hayyah
Nov 16 '18 at 23:15
add a comment |
Thank you for your answer, I'm using ASCII Encoding.
– Imad Abu Hayyah
Nov 16 '18 at 23:06
Lets assume UTF8 so 1 Byte? If the OP was using a US-ASCII only source. One single CodePoint outside that path and you have, possibly, 2 to 4 bytes per char.
– Jimi
Nov 16 '18 at 23:15
What about Arabic characters? Is it each char needs two bytes?
– Imad Abu Hayyah
Nov 16 '18 at 23:15
Thank you for your answer, I'm using ASCII Encoding.
– Imad Abu Hayyah
Nov 16 '18 at 23:06
Thank you for your answer, I'm using ASCII Encoding.
– Imad Abu Hayyah
Nov 16 '18 at 23:06
Lets assume UTF8 so 1 Byte? If the OP was using a US-ASCII only source. One single CodePoint outside that path and you have, possibly, 2 to 4 bytes per char.
– Jimi
Nov 16 '18 at 23:15
Lets assume UTF8 so 1 Byte? If the OP was using a US-ASCII only source. One single CodePoint outside that path and you have, possibly, 2 to 4 bytes per char.
– Jimi
Nov 16 '18 at 23:15
What about Arabic characters? Is it each char needs two bytes?
– Imad Abu Hayyah
Nov 16 '18 at 23:15
What about Arabic characters? Is it each char needs two bytes?
– Imad Abu Hayyah
Nov 16 '18 at 23:15
add a comment |
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