Does a hash function have a Upper bound on input length?Why does the padding in Merkle–Damgård hash functions like MD5 contain the message length?Is it theoretically possible to construct a string that contains its own hash value?Hash function in PBKDF2Does this guarantee a unique 32 bit Hash?How to choose the reduction function in rainbow tables?Combining secure hashes with insecure hashes?Advantages/disadvantages of using symmetric encryption function as hash function?Why does a Hashing Function produce good Random Numbers if Input is random?Hash length vs Data lengthWhat does “bits” mean in the context of hash functions?Security of a given hash functionHow many bits in the resultant hash will change, if the x bits are changed in its the original input?
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Does a hash function have a Upper bound on input length?
Why does the padding in Merkle–Damgård hash functions like MD5 contain the message length?Is it theoretically possible to construct a string that contains its own hash value?Hash function in PBKDF2Does this guarantee a unique 32 bit Hash?How to choose the reduction function in rainbow tables?Combining secure hashes with insecure hashes?Advantages/disadvantages of using symmetric encryption function as hash function?Why does a Hashing Function produce good Random Numbers if Input is random?Hash length vs Data lengthWhat does “bits” mean in the context of hash functions?Security of a given hash functionHow many bits in the resultant hash will change, if the x bits are changed in its the original input?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
I came across this Answer stating (just a line from the answer):-
The input space is "infinite" and thus it has an infinite amount of values that will collide into a single hash
And in the comments of this answer, there exists a comment of @poncho stating:-
Technically, the input space for the SHA-1 and SHA-2 hash functions is not "infinite"; SHA-1 and SHA-256 inputs are limited to $2^64−1$ bits; SHA-512 is limited to $2^128−1$ bits
In reply to the above comment, the answer'er does accept the above fact. But, I can't seem to understand why?
As there exists a large number of answers, like this who loosely use the term infinite with the input space of hash functions. I tried to resolve the ambiguity via Wikipedia page of MD5 and SHA1, this is the definition of both:-
In cryptography, SHA-1 is a cryptographic hash function which takes an input and produces a 160-bit hash
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value
In both the definition, there exists no mention of input size (in bits) of the algorithms.
QUESTION:-
Does hashing algorithms have an upper bound in the input space?
P.S.:- If the upper bound does exists, then can anyone tell me why isn't the hashing algorithm able to work on input size above the upper bound?
hash sha-1 md5
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
$endgroup$
add a comment |
$begingroup$
I came across this Answer stating (just a line from the answer):-
The input space is "infinite" and thus it has an infinite amount of values that will collide into a single hash
And in the comments of this answer, there exists a comment of @poncho stating:-
Technically, the input space for the SHA-1 and SHA-2 hash functions is not "infinite"; SHA-1 and SHA-256 inputs are limited to $2^64−1$ bits; SHA-512 is limited to $2^128−1$ bits
In reply to the above comment, the answer'er does accept the above fact. But, I can't seem to understand why?
As there exists a large number of answers, like this who loosely use the term infinite with the input space of hash functions. I tried to resolve the ambiguity via Wikipedia page of MD5 and SHA1, this is the definition of both:-
In cryptography, SHA-1 is a cryptographic hash function which takes an input and produces a 160-bit hash
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value
In both the definition, there exists no mention of input size (in bits) of the algorithms.
QUESTION:-
Does hashing algorithms have an upper bound in the input space?
P.S.:- If the upper bound does exists, then can anyone tell me why isn't the hashing algorithm able to work on input size above the upper bound?
hash sha-1 md5
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
$endgroup$
$begingroup$
Not all hash functions but the universe have a limit on the data to store.
$endgroup$
– kelalaka
6 hours ago
add a comment |
$begingroup$
I came across this Answer stating (just a line from the answer):-
The input space is "infinite" and thus it has an infinite amount of values that will collide into a single hash
And in the comments of this answer, there exists a comment of @poncho stating:-
Technically, the input space for the SHA-1 and SHA-2 hash functions is not "infinite"; SHA-1 and SHA-256 inputs are limited to $2^64−1$ bits; SHA-512 is limited to $2^128−1$ bits
In reply to the above comment, the answer'er does accept the above fact. But, I can't seem to understand why?
As there exists a large number of answers, like this who loosely use the term infinite with the input space of hash functions. I tried to resolve the ambiguity via Wikipedia page of MD5 and SHA1, this is the definition of both:-
In cryptography, SHA-1 is a cryptographic hash function which takes an input and produces a 160-bit hash
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value
In both the definition, there exists no mention of input size (in bits) of the algorithms.
QUESTION:-
Does hashing algorithms have an upper bound in the input space?
P.S.:- If the upper bound does exists, then can anyone tell me why isn't the hashing algorithm able to work on input size above the upper bound?
hash sha-1 md5
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
$endgroup$
I came across this Answer stating (just a line from the answer):-
The input space is "infinite" and thus it has an infinite amount of values that will collide into a single hash
And in the comments of this answer, there exists a comment of @poncho stating:-
Technically, the input space for the SHA-1 and SHA-2 hash functions is not "infinite"; SHA-1 and SHA-256 inputs are limited to $2^64−1$ bits; SHA-512 is limited to $2^128−1$ bits
In reply to the above comment, the answer'er does accept the above fact. But, I can't seem to understand why?
As there exists a large number of answers, like this who loosely use the term infinite with the input space of hash functions. I tried to resolve the ambiguity via Wikipedia page of MD5 and SHA1, this is the definition of both:-
In cryptography, SHA-1 is a cryptographic hash function which takes an input and produces a 160-bit hash
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value
In both the definition, there exists no mention of input size (in bits) of the algorithms.
QUESTION:-
Does hashing algorithms have an upper bound in the input space?
P.S.:- If the upper bound does exists, then can anyone tell me why isn't the hashing algorithm able to work on input size above the upper bound?
hash sha-1 md5
hash sha-1 md5
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
asked 8 hours ago
Vasu Deo.SVasu Deo.S
2189 bronze badges
2189 bronze badges
$begingroup$
Not all hash functions but the universe have a limit on the data to store.
$endgroup$
– kelalaka
6 hours ago
add a comment |
$begingroup$
Not all hash functions but the universe have a limit on the data to store.
$endgroup$
– kelalaka
6 hours ago
$begingroup$
Not all hash functions but the universe have a limit on the data to store.
$endgroup$
– kelalaka
6 hours ago
$begingroup$
Not all hash functions but the universe have a limit on the data to store.
$endgroup$
– kelalaka
6 hours ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
Does hashing algorithms have an upper bound in the input space?
They can, but they don't have to and it depends on their specification.
- All Merkle-Damgård based hash functions do have an upper limit, because appending the message length simplifies the security proof and the backdoor-resistance of the function and they usually use a fixed-length encoding of the length.
- SHA-3 (Spec PDF) does not have such a limit as it's based on the sponge-construction.
- Skein (Spec PDF) does have a limit of $2^96$ bytes.
- Blake2 (Spec PDF) has a limit of $2^128$ bytes.
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
$endgroup$
$begingroup$
Oh, Thanks (+1). I totally forgot the fact that during the process of computing message digest of a message (in MD5 and SHA1), it's original length in bits is appended to the padded bits. Therefore, if we use message length > that length, we won't be able to append the actual length of the original message (as it would either result in overflow or would get truncated using a modulo operation which would lead to incorrect length).
$endgroup$
– Vasu Deo.S
7 hours ago
$begingroup$
BTW could you please tell me why answers like this still refer to the input space be infinite in length?
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
@VasuDeo.S probably because for most purposes "infinite" is a good approximation of "messages shorter than 2^64 bit" (which is > 1 million terabyte).
$endgroup$
– SEJPM♦
6 hours ago
$begingroup$
Thanks for taking time to answer my question!!
$endgroup$
– Vasu Deo.S
6 hours ago
add a comment |
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1 Answer
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oldest
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1 Answer
1
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oldest
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active
oldest
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$begingroup$
Does hashing algorithms have an upper bound in the input space?
They can, but they don't have to and it depends on their specification.
- All Merkle-Damgård based hash functions do have an upper limit, because appending the message length simplifies the security proof and the backdoor-resistance of the function and they usually use a fixed-length encoding of the length.
- SHA-3 (Spec PDF) does not have such a limit as it's based on the sponge-construction.
- Skein (Spec PDF) does have a limit of $2^96$ bytes.
- Blake2 (Spec PDF) has a limit of $2^128$ bytes.
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
$endgroup$
$begingroup$
Oh, Thanks (+1). I totally forgot the fact that during the process of computing message digest of a message (in MD5 and SHA1), it's original length in bits is appended to the padded bits. Therefore, if we use message length > that length, we won't be able to append the actual length of the original message (as it would either result in overflow or would get truncated using a modulo operation which would lead to incorrect length).
$endgroup$
– Vasu Deo.S
7 hours ago
$begingroup$
BTW could you please tell me why answers like this still refer to the input space be infinite in length?
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
@VasuDeo.S probably because for most purposes "infinite" is a good approximation of "messages shorter than 2^64 bit" (which is > 1 million terabyte).
$endgroup$
– SEJPM♦
6 hours ago
$begingroup$
Thanks for taking time to answer my question!!
$endgroup$
– Vasu Deo.S
6 hours ago
add a comment |
$begingroup$
Does hashing algorithms have an upper bound in the input space?
They can, but they don't have to and it depends on their specification.
- All Merkle-Damgård based hash functions do have an upper limit, because appending the message length simplifies the security proof and the backdoor-resistance of the function and they usually use a fixed-length encoding of the length.
- SHA-3 (Spec PDF) does not have such a limit as it's based on the sponge-construction.
- Skein (Spec PDF) does have a limit of $2^96$ bytes.
- Blake2 (Spec PDF) has a limit of $2^128$ bytes.
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
$endgroup$
$begingroup$
Oh, Thanks (+1). I totally forgot the fact that during the process of computing message digest of a message (in MD5 and SHA1), it's original length in bits is appended to the padded bits. Therefore, if we use message length > that length, we won't be able to append the actual length of the original message (as it would either result in overflow or would get truncated using a modulo operation which would lead to incorrect length).
$endgroup$
– Vasu Deo.S
7 hours ago
$begingroup$
BTW could you please tell me why answers like this still refer to the input space be infinite in length?
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
@VasuDeo.S probably because for most purposes "infinite" is a good approximation of "messages shorter than 2^64 bit" (which is > 1 million terabyte).
$endgroup$
– SEJPM♦
6 hours ago
$begingroup$
Thanks for taking time to answer my question!!
$endgroup$
– Vasu Deo.S
6 hours ago
add a comment |
$begingroup$
Does hashing algorithms have an upper bound in the input space?
They can, but they don't have to and it depends on their specification.
- All Merkle-Damgård based hash functions do have an upper limit, because appending the message length simplifies the security proof and the backdoor-resistance of the function and they usually use a fixed-length encoding of the length.
- SHA-3 (Spec PDF) does not have such a limit as it's based on the sponge-construction.
- Skein (Spec PDF) does have a limit of $2^96$ bytes.
- Blake2 (Spec PDF) has a limit of $2^128$ bytes.
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
$endgroup$
Does hashing algorithms have an upper bound in the input space?
They can, but they don't have to and it depends on their specification.
- All Merkle-Damgård based hash functions do have an upper limit, because appending the message length simplifies the security proof and the backdoor-resistance of the function and they usually use a fixed-length encoding of the length.
- SHA-3 (Spec PDF) does not have such a limit as it's based on the sponge-construction.
- Skein (Spec PDF) does have a limit of $2^96$ bytes.
- Blake2 (Spec PDF) has a limit of $2^128$ bytes.
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
answered 7 hours ago
SEJPM♦SEJPM
30.5k6 gold badges62 silver badges146 bronze badges
30.5k6 gold badges62 silver badges146 bronze badges
$begingroup$
Oh, Thanks (+1). I totally forgot the fact that during the process of computing message digest of a message (in MD5 and SHA1), it's original length in bits is appended to the padded bits. Therefore, if we use message length > that length, we won't be able to append the actual length of the original message (as it would either result in overflow or would get truncated using a modulo operation which would lead to incorrect length).
$endgroup$
– Vasu Deo.S
7 hours ago
$begingroup$
BTW could you please tell me why answers like this still refer to the input space be infinite in length?
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
@VasuDeo.S probably because for most purposes "infinite" is a good approximation of "messages shorter than 2^64 bit" (which is > 1 million terabyte).
$endgroup$
– SEJPM♦
6 hours ago
$begingroup$
Thanks for taking time to answer my question!!
$endgroup$
– Vasu Deo.S
6 hours ago
add a comment |
$begingroup$
Oh, Thanks (+1). I totally forgot the fact that during the process of computing message digest of a message (in MD5 and SHA1), it's original length in bits is appended to the padded bits. Therefore, if we use message length > that length, we won't be able to append the actual length of the original message (as it would either result in overflow or would get truncated using a modulo operation which would lead to incorrect length).
$endgroup$
– Vasu Deo.S
7 hours ago
$begingroup$
BTW could you please tell me why answers like this still refer to the input space be infinite in length?
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
@VasuDeo.S probably because for most purposes "infinite" is a good approximation of "messages shorter than 2^64 bit" (which is > 1 million terabyte).
$endgroup$
– SEJPM♦
6 hours ago
$begingroup$
Thanks for taking time to answer my question!!
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
Oh, Thanks (+1). I totally forgot the fact that during the process of computing message digest of a message (in MD5 and SHA1), it's original length in bits is appended to the padded bits. Therefore, if we use message length > that length, we won't be able to append the actual length of the original message (as it would either result in overflow or would get truncated using a modulo operation which would lead to incorrect length).
$endgroup$
– Vasu Deo.S
7 hours ago
$begingroup$
Oh, Thanks (+1). I totally forgot the fact that during the process of computing message digest of a message (in MD5 and SHA1), it's original length in bits is appended to the padded bits. Therefore, if we use message length > that length, we won't be able to append the actual length of the original message (as it would either result in overflow or would get truncated using a modulo operation which would lead to incorrect length).
$endgroup$
– Vasu Deo.S
7 hours ago
$begingroup$
BTW could you please tell me why answers like this still refer to the input space be infinite in length?
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
BTW could you please tell me why answers like this still refer to the input space be infinite in length?
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
@VasuDeo.S probably because for most purposes "infinite" is a good approximation of "messages shorter than 2^64 bit" (which is > 1 million terabyte).
$endgroup$
– SEJPM♦
6 hours ago
$begingroup$
@VasuDeo.S probably because for most purposes "infinite" is a good approximation of "messages shorter than 2^64 bit" (which is > 1 million terabyte).
$endgroup$
– SEJPM♦
6 hours ago
$begingroup$
Thanks for taking time to answer my question!!
$endgroup$
– Vasu Deo.S
6 hours ago
$begingroup$
Thanks for taking time to answer my question!!
$endgroup$
– Vasu Deo.S
6 hours ago
add a comment |
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$begingroup$
Not all hash functions but the universe have a limit on the data to store.
$endgroup$
– kelalaka
6 hours ago