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…limitations of this hash-based stream cipher design?

One of the limitations of this hash-based stream cipher design would be that it does not offer any kind of “authentication”, nor any kind of “integrity-protection”.

Maybe you just forgot to describe how you will be handling authentication and integrity-protection, but it’s important not to forget about it.

I intend to use Skein…

That raises the question why you aren’t simply using Threefish as a well-vetted block cipher. After all, the design of Skein is based on the Threefish tweakable block cipher!

In the unlikely case you really need a stream-cipher because something prevents you from using a block-cipher, you could create one based on Threefish, which is bound to provide a bit more speed (when implemented correctly) than building a cipher based upon the Skein Hash Function Family.

Nota Bene:

As it’s not clear to me why someone would try to create a hash-based stream cipher while well-analyzed stream ciphers are available, I have skipped cryptanalysis – which means that your design may (or may not) have security issues I did not check on. In the end, I guess I somewhat chime in with Stephens comment and simply don’t seem to have that “scientific interest” you mentioned in your comment.

…limitations of this hash-based stream cipher design?

One of the limitations of this hash-based stream cipher design would be that it does not offer any kind of “authentication”, nor any kind of “integrity-protection”.

Maybe you just forgot to describe how you will be handling authentication and integrity-protection, but it’s important not to forget about it.

I intend to use Skein…

That raises the question why you aren’t simply using Threefish as a well-vetted block cipher. After all, the design of Skein is based on the Threefish tweakable block cipher!

In the unlikely case you really need a stream-cipher because something prevents you from using a block-cipher, you could create one based on Threefish, which is bound to provide a bit more speed (when implemented correctly) than building a cipher based upon the Skein Hash Function Family.

Nota Bene:

As it’s not clear to me why someone would try to create a hash-based stream cipher while well-analyzed stream ciphers are available, I have skipped cryptanalysis – which means that your design may (or may not) have security issues I did not check on. In the end, I guess I somewhat chime in with Stephens comment and simply don’t seem to have that “scientific interest” you mentioned in your comment.

…limitations of this hash-based stream cipher design?

One of the limitations of this hash-based stream cipher design would be that it does not offer any kind of “authentication”, nor any kind of “integrity-protection”.

Maybe you just forgot to describe how you will be handling authentication and integrity-protection, but it’s important not to forget about it.

I intend to use Skein…

That raises the question why you aren’t simply using Threefish as a well-vetted block cipher. After all, the design of Skein is based on the Threefish tweakable block cipher!

In the unlikely case you really need a stream-cipher because something prevents you from using a block-cipher, you could create one based on Threefish, which is bound to provide a bit more speed (when implemented correctly) than building a cipher based upon the Skein hash function.

Nota Bene:

As it’s not clear to me why someone would try to create a hash-based stream cipher while well-analyzed stream ciphers are available, I have skipped cryptanalysis – which means that your design may (or may not) have security issues I did not check on. In the end, I guess I somewhat chime in with Stephens comment and simply don’t seem to have that “scientific interest” you mentioned in your comment.

…limitations of this hash-based stream cipher design?

One of the limitations of this hash-based stream cipher design would be that it does not offer any kind of “authentication”, nor any kind of “integrity-protection”.

Maybe you just forgot to describe how you will be handling authentication and integrity-protection, but it’s important not to forget about it.

I intend to use Skein…

That raises the question why you aren’t simply using Threefish as a well-vetted block cipher. After all, the design of Skein is based on the Threefish tweakable block cipher!

In the unlikely case you really need a stream-cipher because something prevents you from using a block-cipher, you could create one based on Threefish, which is bound to provide a bit more speed (when implemented correctly) than building a cipher based upon the Skein Hash Function Family.

Nota Bene:

As it’s not clear to me why someone would try to create a hash-based stream cipher while well-analyzed stream ciphers are available, I have skipped cryptanalysis – which means that your design may (or may not) have security issues I did not check on. In the end, I guess I somewhat chime in with Stephens comment and simply don’t seem to have that “scientific interest” you mentioned in your comment.

…limitations of this hash-based stream cipher design?

One of the limitations of this hash-based stream cipher design would be that it does not offer any kind of “authentication”, nor any kind of “integrity-protection”.

Maybe you just forgot to describe how you will be handling authentication and integrity-protection, but it’s important not to forget about it.

I intend to use Skein…

That raises the question why you aren’t simply using Threefish as a well-vetted block cipher. After all, the design of Skein is based on the Threefish tweakable block cipher!

In the unlikely case you really need a stream-cipher because something prevents you from using a block-cipher, you could create one based on Threefish, which is bound to provide a bit more speed (when implemented correctly) than building a cipher based upon the Skein hash function.

…limitations of this hash-based stream cipher design?

One of the limitations of this hash-based stream cipher design would be that it does not offer any kind of “authentication”, nor any kind of “integrity-protection”.

Maybe you just forgot to describe how you will be handling authentication and integrity-protection, but it’s important not to forget about it.

I intend to use Skein…

That raises the question why you aren’t simply using Threefish as a well-vetted block cipher. After all, the design of Skein is based on the Threefish tweakable block cipher!

In the unlikely case you really need a stream-cipher because something prevents you from using a block-cipher, you could create one based on Threefish, which is bound to provide a bit more speed (when implemented correctly) than building a cipher based upon the Skein hash function.

Nota Bene:

As it’s not clear to me why someone would try to create a hash-based stream cipher while well-analyzed stream ciphers are available, I have skipped cryptanalysis – which means that your design may (or may not) have security issues I did not check on. In the end, I guess I somewhat chime in with Stephens comment and simply don’t seem to have that “scientific interest” you mentioned in your comment.